In 2009, I found a mortgage offer on Maxbounty that paid $30+ for the first page signup.
Being the genius I was, I filled out the form myself multiple times (no proxies) using not so legit information (first name: alkjdfasklfjasd, address: 3289432th ave)
I made $200 in 20 minutes and thought I was a genius.
Later that night, Maxbounty perma banned me without warning 
Yes, this is a real story, and no, I don't regret it. Bad mistakes make for great memories.
What are some stupid mistakes you've made?
edit:
I meant to write "Stupidest", not "Stupid" in the thread title.
Not checking links before submitting campaigns lol, If only I learned to double check i'd be able to buy a nice car with the money that was lost haha XD
I make mistakes everyday though, but I chuckle and move on
!
That's a good one haha I bet your lips were full frothin for your first $200 paycheck
When I first started making money online I was adsensing like a boss, id make blogspots about credit, insurance etc and every lunch time I'd run into the computer labs and click on all my ads and I thought I was making $100 day, by the end of 2 weeks I had over $2000 in the account and I was peaking from it haha but then instant ban from adsense for life haha
Makes me laugh at how noob I was back then, fun times!
going into five figures media buy without having adserver, without having my banners tested first, and buying remnant with jacked up CPM
haha similar to Maynzie, not checking links, and when using multi uploader not checking file directories and using same sex images for straight campaigns but still managing to profit.
Also forgetting when niche targeting forgetting to actually target the "niche" and burning through ad spend like NO TOMORROW! that's where the monies lost, laugh and move on as maynzie said, daily mistakes 
Oh man, I'm with you on that Jax! Haven't done anything dumb enough to loose a nut, yet, but it's the daily mistakes, not checking links, getting campaigns switched up, stuff like that.
Accidentally leaving cloaked campaigns redirecting to the wrong offer up to XX,XXX in adspend.
Probably my ill-fated "Girlfriend for Christmas" campaign targeted at Jews.
Running with aff networks and ad networks known for theft
Names! Names!
Saying yes to my Microsoft display rep when he asked the question can we run this uncapped? And run of network? When the ad server had a 36 hour delay on stats. Started seeing my female demo ads showing on every site on the internet like the homepage of digg. Saw 200k in revenue come in, in 18 hours and thought we were killing it. Then later realized I'd spent 350k to make that 200k. Lost 150k in a short 18 hours. Ouch.
Downloaded few millions Email lists from blackhatteam and set up auto responder on my domain and spam the offer hell out of this list.
Managed to make $300 in profit (only domain and hosting cost involved) however I soon received a permanent disable of my main domain by my hosting. Lesson learnt!
When I was making my first campaign I copied an entire ppc campaign on KeywordSpy, made a similar landing page and got the same offer. I thought I would get rich instantly so I set my limit to 2k per day on adwords, and then I ended up spending almost 2k, getting about 500$ in revenue...
...and I got banned from adwords the next day (because of my landing page).
I wanted to give up on affiliate marketing after that, so I went to warrior forum and bought a couple of WSOs and then an "automated income clickbank software"... As you can imagine none of those products worked, so I asked for refund for the clickbank software, but I kept the WSOs.
I stopped creating campaigns for about 3 months and spent my time reading forums and analyzing other affiliates campaigns, then I decided to put all that I had learned in action and 4 months after taking action I got my first 5 digit/day profit.
I increased the bid on a FB campaign by $5 instead of by $0.05 (with daily budget set to $5k). I lost 2 weeks worth of profit in 20 minutes.
Around when I first started running dating on POF I decided I would setup a richmen campaign and see if I could make it work. Get the ads approved and all and let it run for about 2 days to try and get a rough idea of the cvr% I could get and the cvr % was about 1%. So I was like WTF?!? My AM said this offer was seeing pretty good numbers for this offer, and yet my numbers are absolute shit. So I basically said ah fuck it i'll just try another offer, then a few months later I was looking through my paused POF campaigns and look back at the Richmen campaign I had setup to find out that I was targeting males not females. FML
But it still makes me lol that I was able to get a few conversions from males for richmen 
Funny to see this thread as I literally just made a mistake before logging into here...
Targeted a UK offer at US traffic on POF - wondered for ages why I wasn't getting conversions.
Weird, I managed to get 1 conversion - not a clue how that happened!
When I copied my pof campaign that was targeting US so that I could target canada I forgot to change the country to CA. So I was basically running 2 campaigns exactly the same at the same time. Luckily I don't have a big testing budget yet so my loss was very small.
My biggest mistake was not milking a big campaign as hard as i could, i seem to always do it.
The worst time was in 2006, it wasn't technically a "Campaign" but it was using affiliate offers and it had some BIG potential. At the time i didn't realize so i just let it run in smaller numbers, i didnt understand exactly what i was promoting, or how, but the profit was around 500% ROI. I was spending $400 or so a day, but didn't feel the need to go any higher. After 40 days it completely died, and i looked back and realized i could have been spending $2000+ a day.
So for future big campaigns, MILK THEM WHILE THEY'RE HOT!
Bidding $9.7 instead of $0.97 on MSN Adsenter for a keyword that didn't turn out to convert, but had a lot of traffic. Those decimal errors sneak in everywhere... Burned about $2K in a few hours. Learned to be really careful how much money is on my VISA, at least when dealing with traffic sources that auto-bill you.
Adcenter. A campaign wasn't approved till weeks later. Yes weeks. Totally forgot about the campaign till I glanced through my cpvlab stats and found a (-$5000+) in red in one of the campaigns. Best thing was, the offer was long gone by the time traffic was running.
Lol I'm another offender of not checking my URLs
back in the hay day of facebook , when dating was as simple as get a high ctr and profit, i set a campaign to 5.00 cpm instead of .50 cpm and spent a few grand in a hour or so. Did the same damn thing before when i was really new in the game doing email submit polls on adwords and bid 5.00 on keywords, blew some change on that to. these are the kind of mistakes you look back at and laugh but its very easy to make these mistakes that could kill you , especially if your new in the game and you take a hit of a few grand.
my mistake is not exactly bidding and all but something more WIERD!! i bought myself an ultra luxurious car backed by a single campaign!!..the problem came in when thAt campaign died and i still had to pay my huge monthly installments !! phew..the operating funds were reduced to just a few grands before i sold off that beauty
!!
Running paid traffic while the server was offline. Not so sure if this is the stupidest possible, but It sure gave me a massive headache.
Set my CPM to $42 on POF instead of 0.42 about six months back on a campaign with $300/day budget, thankfully I contacted Ben and the team and they were kind enough to readjust to $0.42 and put the spent money back in my account not many traffic sources would do that Im sure 
Another stupid one was restarting an old campaign without checking if the offer was still live that cost me over $700, I complained to my AM as to why he had not told me the offer was down, he responded by giving me a $0.20 bump on another offer I was running.
I am generally constantly making little mistakes, its all good fun 
Listening more to an ad rep than my money.
I bought the "FB Ad Manager" from a "friend" for $50,000 because I was trying to do the right thing. A few days later BANG C&D from Facebook. Trolololo YOLO.
Working for a company which didn't have a base. I lot a good amount and then I was on the real track. From then i never joined a network without knowing its detail. Atleast verified payment history 
Accidentally created 2 different campaigns, but on the same site/placement. Then I get into a bidding war with myself because of lack of proper organization. I was like wtf does this guy keep bidding against me everytime I increase my bid LOLLLLLLL
Yeah, it was my 2nd campaign ever. I realized very quickly how important organization is for success.
man.. just reading through the thread again makes my balls hurt 
I lost a hefty hit of $ gambling last ASW, is that considered an aff mistake?
Double up and catch up is a 100% way to guarantee you never lose.
*as long as you have an unlimited bank roll and find a casino with unlimited table limits.
Good to know others have issues and share them. I feel like i am dumb @ss half tha time
Added tracking link to offer...then had web designer tweak page and he pulled code...
ran lander with no tracking link / sales link and burned cash.
Put double check system now to prevent that again 