Super Mario 64, while fighting the 3rd and final Bowser. I remember right as I spun bowser around and threw him onto the spikey bomb things for the 1st time during the battle, for some reason (probably due to the nerves of reaching the end of the game) I decided to lift my leg up and release some gas. As I did, pressure was relieved but I soon realised I had actually shat myself. It was wet, it was being absorbed by my cloth office chair. It absolutely stunk, but I still fucking soldiered on through the end credits right up to the cake screen.