anal licking on your boyfriend ???

Sooooo ive always thought it was gross to lick a guys butt but for some odd reason my boyfriend has a realllly nice butt and it's been turning me on. I've been having the urg to kiss it and lick it. I've googled about it and apperently it's very common...... so I'm not weird lol foreal google it lol Obviously it would be after a shower and he's clean.