I had a chao named Nico (Because he was born with a smile, and the Japanese onomatopoeia for smiling is Nico).
Its a sad story really. I was playing as Knuckles and Nico was asleep. For those of you who have the PC version of SADX, for some odd reason the Escape key is the action key.
I tried to pause for a sec, so naturally I thought the escape key pauses. Instead it punched Nico into a wall. Now Nico has "Brain Damage" because he always has half-lid eyes and a swirl. I have a screenshot floating around on my pc somewhere, but Im too lazy to find/upload it.