I've just always found them all very humorous.
Floggin the dolphin
Shakin' up the soda
Spankin' the dog
Arm Wrestling with your buddy (or thumb wrestling for some ;) )
Playing the Slot Machine
Weekends with Grandpa (crap, where's that delete key?!!!??!!?)
C'mon, you pervs. Oh, and you can use some for the ladies, too.