It's pretty much clear with sex, even using a condom. What is not clear is why there are two big TV sets on the wall practically right next to each other. And what's more, they are mounted at different angles! By the way, the man can clearly see how much he enjoys his girlfriend. Although to be honest she looks like a plank!
Sleeping with a stranger is no big deal. Getting naked and having sex on a rushing bus is top notch! Maybe for the busty brunette is okay, but I personally have never seen anything like this. Impressive and exciting!