A bee in layman's terms comes from the movie, X-Files: Fight the Future. The scene when this comes into play is when Mulder and Scully try to kiss -- and a dang bee comes and stings her and they end up NOT kissing.
Another example is when Tony and Ziva try to kiss in a room and someone opens the door. This is another example of a bee, only this time only a figurative bee, not a literal one.
'Hey you -- stop being such a bee -- you're interrupting me and my girl here from kissing...'