This one's not mine, but it's very funny, so I thought I'd share:
A colleague of mine was working the tower, and he accidentally pressed the foot pedal while looking through the binoculars. As he was lowering the binoculars view to look at his "middle leg" he shouted: "DAMN IT, MY C*CK IS SOOOO HUGE"
I don't have to tell you the look on his face when he realized the mic was on and he was transmitting.
And another thing that happened recently in the Area Control Center here in Skopje. There's a company called Mediterranean Air Freight whose ICAO code is MDF and callsign is Medfreight.
However, when we coordinate internally between sectors, we call him Madafa*ka (the three letter ICAO designator)

and one time, a controller presses the mic and goes: Madafa*ka 123, climb FL.....mmmmmmmm correction, Medfreight 123......" the entire room was cracking, we couldn't work for the next 10 minutes or so
cheers