Charlie Sheen actually had a pretty brief cameo on Friends back in the early days. Playing a Navy officer named Brian, who was an old flame of Phoebe’s. Not a bad guy, definitely a better man than Charlie Sheen in reality.

She was excited that he came back into her life for another brief interim. But she gets chicken pox and is terrified to learn that he never had it.

So they both get it together willingly. I don’t think it was long after this episode that they actually made a chicken pox vaccine. They both had to suffer, like I did as a kid.