Awhile back our USAF unit was the 19th Fighter Sqdrn, aka "The Gamecocks". While flying a 4 ship of F-16's thru Cleveland center's airspace, the following transmissions happened on initial check-in:

"Cleveland, C ock 01 at FL 390."

ATC: Silence.

"Cleveland, C ock 01 at 390."

ATC: Nothing. Crickets.

Tried twice more. Dead silence.

Finally, a male controller comes on--laughing--and says "C ock 01 contact Chicago on 257.1...oh, and give us a call when you land at the following phone #. You C ocks have a good day..."

Turns out the female controller on duty would not respond to such a non-politically correct call sign. By the time we landed the base General had already talked to center, told the offended female to "get her mind out of the gutter", and explained that the call sign had been in use by our squadron since WW I...