Told to me by another pilot, overheard going into DFW one night.
Female ATC: Airline123 descend and maintain FLxxx.
Airline 123: Descend FLxxx pilots discretion.
Female ATC reams the pilot: DESCEND NOW! IF I WANTED YOU TO GO AT PILOTS DESCRETION, I WOULD HAVE SAID.......BLAH BLAH BLAH.
Huge pregnant pause, dead quiet.
Finally an unidentified voice says: Was I married to you once?