your only problem is like you said you live where gay's and Bi's are seldom and look down upon. See were I live its like a mini San Fransico everyone in the city is Pro-gay and they never see a problem with it. I'm not like most folks in my city though. I dont have a problem with gays or BI's but be honest. You see your friend as a freak because you have known him for a while and you don't suspect shit like that. For me if I found out my friend shoved a dildo up his ass I would be ok with it and stuff. I would talk and hangout with him but I would really have to think about having him stay at my place for a night. You won't see your friend the same until you forget this but don't just ignore him just act the same and shit. Oh and if you feel like pulling one of those "confront and talk about it with him" shenanagins DONT!!! Your friend will hate you for even mentioning and dont try to understand what he likes about it ( don't shove something up your ass ) Just chill with him and forget about it.