Ahh heck, I didn't tell this one...
Long long ago, in a galaxy far far away... I found myself in the right seat of an ATR-42 during a Part 91 repositioning flight. I won't explain how that came to pass to keep the innocent safe... but there I was.
Obviously I knew the guy in the left seat, and we were telling jokes back and forth on the "intercom" while he let me hand-fly the thing at FL230, which I wasn't doing so hot at... but we weren't hurtling toward Earth in a death spiral, so he was ignoring me mostly. It was sometime around 3AM in the morning over Texas somewhere.
Anyway... after about a half hour of jokes back and forth, after I tell the punchline to one of them, we hear someone key up and laugh out loud on the radio. My friend looks over at me with wide eyes, and says... "Which way are you pushing that switch?"
You see... in the ATR... we were getting some background noise into the intercom, so he'd selected the manually keyed intercom mode and... the trigger switch on the yoke goes TWO directions... you pull it TOWARD you to transmit, and push it AWAY from you to talk on the ICS.
Guess which direction I'd been going...
My last transmission was "What do you mean, which way am I pushing the switch?!"
The howls of laughter from the other airliner on the otherwise dead quiet frequency, and the rather simple admonition from Ft. Worth Center... "Stuck mic." (Which wasn't quite accurate, but got the point across...)
All I wanted was to rewind 30 minutes and have the foresight to ASK how to run the intercom properly, as my heart sank into my shoes.
My friend just tipped his head back and laughed out loud harder than he had at any of the jokes and said, "You push that switch AWAY from you to talk on the Intercom, Nathan!"
Still funny after all these years...