i was doin an unemployment course years ago and snapped, saw colours and started cracking up laughing and we were sposed to be replanting this big cactus thing but i beat it to death with a spade much to the astonishement of those around. lasted about 5 minutes? 1 minute? dunno.
not sure if it was a flashback or just a mental fit. was doing a lot of acid and speed at the time.