These jokes work equally well regardless of the sex, gender, or
orientation of the characters.
Chris and Blake are musicians in the orchestra.
“Hey, Blake, is it true you're dating Dana, the French hornist?
How is that?”
“I like them, but it took some getting used to.”
“Every time they kiss me, they stick their fist in my butt.”
Morgan and Reese are making out in the front seat of Reese's car.
Reese pauses and asks “Would you like to go in the back seat?”
“No, thanks,” replies Morgan, and they continue making out.
A while later Reese asks “Now would you like to get in the back
seat?” Morgan shakes their head decisively. “No!” They continue
to make out.
Things are getting very sweaty, and the windows are steaming up.
Reese says “I understand you don't want to get in the back, and I
don't want to pressure you, but can you just tell me why not?”
“I want to stay up here, with you!”
My grandfather told me that second one.