OfferUp is the place where I've had the most "odd" encounters with people, and as far as I can see there's no block option. This isn't even to mention how abysmally slow the app is to load and use compared to others. I get a notification (if I'm lucky) that someone messaged me, and it will take about a minute for the OfferUp screen to load, and another minute while the chat system loads and the keyboard stops overlaying the chat box. Reinstalling didn't fix.