I came home from work the other day and opened the bathroom door to find my roommate's boyfriend sitting on our toilet (the door wasn't locked and I didn't realize he was even there). We both kinda froze for a second and then I closed the door and went into my room until he left. I've only seen him once since — he was making dinner with my roommate the next night — and it was super awkward but neither of us mentioned it. I don't know if he told my roommate what happened or not. Should I say something to her? To him? Say nothing and forget about it? Aghhhh!
Busted in the Bathroom
That is awkward but I think you're overthinking the whole thing. Accidents happen; it's not such a big deal. But since you will likely see this guy again (or all the time!) if things are truly that weird you may want to address it.
I suggest a little humor. The next time they're both around, get up and say something like, "Hey Jake, I need to show you a new fangled invention they just came up with. It's called a door lock." Don't be mean about it, this is lighthearted fun. By addressing it first, you get to set the tone so make it easy, not stressful. Then, let it go. I'll bet almost anything he learned his lesson about locking and you'll never have this particular problem again.