1: An idea so utterly stupid/hazardous that it must be done.
2: An idea of a friend's that is so incredibly stupid and will obviously end in embarrassment/injury that you have to watch it be acted out.
3: An action that is a failure of orgasmic proportions.
Other dumbass:"That could be the most failgasmic thing I've ever heard gimmee some BBs"
2: Your buddy jeff: "hey bro im gonna ride this bobsled down 3 flights of stairs!"
You: "That Failosophy is so failgasmic that it would be criminal not to videotape it for my Youtube channel"
3:Something akin to getting expelled from Kindergarten.