So, I know a certain number of my readers out there are not cat people like I am. And yet, you have friends that are cat people, and you find yourself in unwilling contact with a cat. Or two. Or six.
So, when you're in that situation where you're in your friend's apartment and the cat is staring at you, instead of viewing this as an annoyance, this is a chance for fun.
Assumption: You don't want to touch the cat. Either it won't let you touch it, or you're allergic, or you're not interested touching it in the first place for some other reason like "ew cat hair". Unlike many other cat people, I am willing to admit doing something like taping a piece of bacon to the cat is funny, but this has the disadvantage that it'll likely annoy the cat's owner. So we're concentrating on having fun with the cat without touching it.
The first thing is to look at the cat and develop a Voice. This where you imagine what the cat would sound like if it could talk. I usually prefer a falsetto, but you may prefer something more deep or resonant, depending on how pretentious the cat looks.
Then, wait until the cat is looking at you or staring at something in a reasonably dignified fashion, and using the Voice (out loud, by preference), intone the following phrase, imagining the cat saying it:
"MY BUTT SMELLS LIKE PEACHES!"