One night during a six night stand in the lounge at one of the casinos in Las Vegas, my band was playing its usual rendition of "Play That Funky Music." Just as the part of the song that goes "play that funky music 'til you die." came up, one of the dancers collapsed on the dance floor. Naturally, the party ground to a halt. Minutes later, the paramedics showed up and were unsuccessful in their attempts to revive him. You can imagine the dark humor that ensued for the rest of the week.
After finishing a set as atrium pianist on a cruise ship, I was about to walk up the staircase, which was spiral and majestic, when a passenger approached me and said "Awesome stairway." So I looked at the staircase and nodded my agreement, whereupon the passenger said "No, Stairway to Heaven," which I had just played. I thanked him.
At one point during a gig the guitarist invited one of his young students up to jam on a blues. They're nearing the end of a chorus, and the kid doesn't know where he is. I say "turnaround", to which the young student complies, doing a complete 360, coming around and facing front again with a baffled look on his face.
I believe they covered that in his next lesson.