I'll tell you how I left my DM and every other player speechless.
We were running a modified pathfinder campaign which my GM had called "Easy mode." It was just modified so we didnt die of our own drunken idiocy. Anyway we didn't want to be good guys, we wanted to be asshole mercenaries. My character (a battlemage) was a more business minded kind of guy, hed wring every scrap of money he could out if someone for a job. He'd charge you a thousand to unclog your drain and you'd fucking pay him he's that much of a charmer. However here's the thing, I'm not as smart as I like my character to be.
So we end up trudging through some high nobles palace, thief is nicking anything he can get away with, barbarian is drinking and trying to "get information from" (read: impregnate) the serving girls. Our fighter is having a sparring match with the Lord's son as part of some mission to get in his good graces, and here I am trying to wring this lord for every scrap of cash imaginable to rescue his favorite mistress from an Orc warchief . Seems a pretty standard quest, in and out, stab some filthy greenskins, no questions asked.
So he's being a bit of a tight ass, I wanted his grandfather's sword for our fighter and he was having none of it.
So I roll to tell him something like "Allright, guess your mistress isn't worth a sharpened steel stick. You best hope she likes big, hard, green dick. Cause if you don't add that sword to the mix were walking out."
The DM was feeling lenient, I had to roll a 9 to get the sword, but luck wasn't on my side.
I rolled a fucking one.
The noble was insulted that we would dare use that language in his house and threw all of us out, permanently ending that quest line.
I'd just fucked up what sounded like a fun combat oriented quest for everyone. And ruined our reputation in our "hub town" over a slightly better sword than the one my friend used.
The DM broke the silence with "Uh, that sword was supposed to be a reward for another quest."
Then the thief goes "I could have stolen it, too."
Cue everyone laughing at my dumb ass and me awkwardly sipping my beer.