I know this thread is a few months old, but I've also had this happen during the summer. The way I dealt with it was head on, if you're friends then you can talk about it and try and laugh it off which is what we managed to do. I think if worse comes to worse, you could both agree to just forget that it happened and that it didn't really change anything. Still friends at the end of the day and a few drunken activities shouldn't get in the way of that.

Scotland here