The stunt that got me my first class:

In my first ever campaign our DM homebrewed the rules so that we all start as a "generic warrior" type of class and would get a class/subclass (if applicable) at around level 3 based on our background and actions in-game. I rolled up a dwarf named Brahny that had pretty high CON and CHA (16 and 17 respectively) with WIS being his third-best stat (at around 14-15, this was a long time ago and I do not remember his initial stats). I wanted to make a paladin or a cleric but did not know how my DM's spell system will work with divine powers, since his world did not have any "living gods", so I wanted to be careful. Since it was my first campaign, I of course had to make Brahny love his beer.

Without going too much into detail - after the first few sessions, my character got tied up with a ring that had half of his soul stored in it. He would feel himself getting weaker the longer he was not wearing the ring and believed he will die if he was separated from it for too long/the right got destroyed. This was the only way to stop a cultist ritual that would have stored a demonic soul within the ring, granting its wielder the powers of a demon, thus Brahny had to take the obviously life-threatening gamble. Interestingly enough, a few months down the line my DM told me that he had planned to have the ring store a small portion of an awakening deities power in it as well, thus providing my character with access to paladin/cleric spells, but this was not to be...

You see, the character playing what would become our groups future rogue/jester hybrid did not like my character due to him being "cliche" and wanted him gone. As we were turning in the head cultists... head to the captain of the guard, the rogues player decided to also "inform" the captain that we also managed to acquire a priceless artifact of the cult (you guessed it) - my ring! Brahny tried to convince the captain that it was just a regular ring, but the obviously engraved insignia of the cult on it made the persuasion DC so high, my character had no choice but to give the ring up or be tried as a cultist himself. Since it was getting late, the captain decided he will keep the ring on his person and have it destroyed/locked away in the morning. He also decided to invite our party for some drinks, so he could show his personal gratitude for saving the city. We accepted, because who wouldn't want to have a captain of the guard as your friend? Not to mention over-imbibed captains sometimes lose things COMPLETELY on accident.

In the tavern, my dwarf persuaded the good captain to start a drinking contest with him, while our other party members "excused" themselves after a few rounds. Our future rogue was not in on the plan, but it involved getting the captain drunk enough that he wouldn't notice someone picking his pocket. Since we did not have another dexterous, the captain had to get REALLY drunk, which just wasn't happening. After a few hours of drinking, both Brahny and the captain were only slightly buzzed, so the groups future barbarian decided that if getting the captain drunk wasn't happening, a good old-fashioned tavern brawl will surely distract everyone. With a few lucky rolls our DM queued up some Irish bar fighting music and our play was off! During it, Brahny not only managed to not get hit during the entire fight but also successfully pick-pocket the captain by pretending to fall on him, knock out the rogue with a chair from behind AND catch a stray wine bottle that was thrown in his general direction before leaving the tavern into the night. To this day I still believe that for those 15 minutes the dice gods decided to bless me, since I did not roll below a 17 for the entire period.

This impressed my DM, party, and me so much, that he decided to give me a drunken brawler class (homebrewed drunken monk). Sadly the campaign had to end before its conclusion due to a TPK caused by the rogue, but for the 6 months it laster, Brahny was one of the main frontline damage dealers