Ramfangled

You've been "ramfangled" when you're doing something (an activity or sport etc.) and things are going perfectly in your favor, then at the last second the situation turns on you and you end up losing or getting fucked over.

Matt was bowling a perfect game untill in the last frame; he got ramfangled when his ball hit a dent in the floor and hit the gutter causing him to lose the tournament.