First game of D&D ever (1979), arrived late to session (playing out on bikes- I was 11) rolled up 1st level Magic User (took an hour- DM in a bad mood, and he's 13 years old- the epicentre of mean).
On the way to the dungeon, rest of guys waiting at door (about 5 minutes down the path)- encounter: 1 kobold, it gets init on me and kills me dead.
The other guys laugh so much that I run away in shame.
Don't play D&D again for two years, return to the game as a DM (aged 13), been getting my own back ever since.
Side salad- killed a PC (Ghoul) as part of a semi-massacre (3 PCs dead out of 5), party retreats to town to recruit. Roll up new guys- go back to dungeon, meet same Ghouls (now with added PC members) = TPK.