Charlie Sheen guest stars on Friends as Ryan, an old flame of Phoebe's that she gives chicken pox to when he's in from the Navy on leave.
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Friends Season 2 Episode 23 Quotes

(to Phoebe) Ryan's been underwater. He's just going to be glad you don't have barnacles on your butt.

Monica

Phoebe: You don't want to see a face that's covered with pox.
Ryan: Your face could be covered with lox, I wouldn't care!