The term used to describe someone who hogs the conversation. Who just won't shut up, babbles on forever taking over the conversation and really has nothing important or interesting to say (rather like a filibuster)
We never could get a word in edgewise because Timmy had a case of verbal diarrhea last night.
Jack: Dude, my wife blew a fuse last night when she saw me chatting with your wife and kept rambling on about how unfaithful I am. To top it off, she didn't let me say a word. George: Sounds she had an extremely bad case of verbal diarrhea.