If I had to choose... I'd say that strange sex scene from Troll II.
The one with the corn.
The main antagonist just randomly has corn-related orgasm with a lonely teenager. Then he gets covered in popcorn.
Why? It never says!
WHAT JUST HAPPENED?!
As long as we are on the subject of Troll 2, how about that ending. That was crazy and weird. Also, how about that Troll Corus or the changing of people into Troll monsters in the first Troll movie?