Umm... probably Cho-Marisa just for sheer disturbance factor. I don't mind MANnosuke too much but I think of them more as different people so... it kind of helps on that @_@
I also don't like similar things that seem to completely throw off a character's established personality (Various Ran portrayls, Tsundere Alice, and I never thought of Wriggle or Utsuho as being particularly stupid enough to earn Team 9 or (6) positions)...
Also I rather enjoy the McDonald MAD Mixes (McRoll, etc. etc.) - I keep a whole playlist of em. But with that said, I enjoy MAD mixes anyway for no understandable reason.