The awkward silence that results when someone informs you that your zipper, or fly is open. The person with the unzipped pants zipper is likley to draw a blank when thinking about how to reply to such an embarrassing observation.
*Brian, Pete, and Pete's crush are at party, having a three way conversation*
Brian: "Hey Pete, XYZ! (examine your zipper)
*Long Awkward Flylence*
Pete: "Ooops (Looks away) Shit happens!"