Man, your fly is open!

How do you tell a man that his fly is open?

I mean, do you just walk up to him and tell him? Especially if he is a stranger? 

What if he is a person in authority? Or a VIP?

During college, this is one of the easiest thing to do. Humiliation for the person and if luck is against him, the whole class might know about it.

It happened to me once and the guy just said to me, you are doing a "Bill Clinton". Huh? I actually did not get at all what he was trying to convey until I went to the toilet. Even then I needed some time to really get that he was trying to warn me.

Hmmmm...too complicated for my taste. For me, maybe the best line for this type of situation is : "Man, your fly is open man. Better zipped it up before your little man decide to peek out"

And just imagine if this happens when he decided to go commando (a topic which I have posted before)