I would have a serious problem with this guy !! I'm not a prude, but there is a time and a place for things. This bloke is totally unprofessional, if he did that in my place of work he would have been disciplined by now. You can't sit at your desk and talk about porn all day, bring in porn, and conduct lewd behaviour in public places (and yes, office toliets are public places). I would report to HR and I wouldn't give a fcuk if he knew it was me or not. But thats just me.