What is a "Crack Pairing"? Good question. I would think it would be a pairing where if you wrote a fan fic about it people would say "crack pairing!". (Wow, circular definition much?)
Maybe it would involve people who move in such different circles that it would be surprising that they've even met. Maybe it would involve an age difference. Maybe it would involve personality types that you wouldn't expect to go together.
However, even some one the most unlikely pairings often have pictures associated with them.
Yuu-chan-Mai-chan
Johnson - Ai-chan
Mako-chan - misono (one I completely made up for yucks, and then one day this appeared:)
What sorts of crack pairings do you guys like?