Oh gawd. I just recalled another mannerism from uh, someone in my close family. "But!" When nobody is listening 'cause we're all fed up, and we're no longer asking polite follow-up questions because it's time for someone else to speak, or at the very least to change the subject... after a short silence this person will just look up and say "But! Did you know, bla-bla-bla" and go on for another twenty minutes. Drives me crazy.

And no, it's not the real "Hey! I just remembered something I have to tell you!" type of "but"...