the stupidest time i died was when i was using mr.game&watch's specail and then moved off the edge to hit the enemy again but the octopus didn't go up he just fell and i died and lost the match because of it!!!
Well, I cannot think of many at this moment, but one time when using Bowser in a 300% match, I used his side special move (Flying Slam) and grabbed my opponent, which gives an instant win when fighting with 300%, but when I jumped upwards I ran into the explosion from one of the smart bombs so I died and he lived (I always play 300% with a large amount of smart bombs)