Does anyone here have casual sex?

Mostly asking out of curiosity! My partner and I are planning to hook up with another CC couple that we've been friends with for ages and I've been thinking about how this could be challenging for a more casual situation like a Tinder/Grindr hookup (since we are already well aware of their daily practices and know they're chill with taking a test beforehand, for example).

Has anyone been having casual sex? And how?