My advice would be don't do it unless you're absolutely sure your friendship will survive.
I was real close to my best friend in high school and we wound up doing stuff one night, which I never saw coming. I won't bore you with the story but suffice to say, it got awkward after it happened and it wound up destroying our friendship. Within a year or two later, I was completely out of his life (partially due to his getting married with a girl that was friends with us both and I have always suspected she found out what we did and wanted him to stop talking to me).
To this day, I regret doing it. Sure, it was fun for that night, but it really did cost me my best friend. It doesn't always turn out bad, but IMHO it wasn't worth the risk.
The same thing happened to me. My best mate and I did the wild thing one night and that was the end of the friendship. I got dumped within two weeks… For a one time thing, you have to ask is the friendship worth loosing. It cost me a mate of 18 years standing. :cry2: