Top 10 Unexpected Celebrity Cameos in FRIENDS

Christina Applegate
Season 9, “The One with Rachel’s Other Sister”
Season 10, “The One Where Rachel’s Sister Babysits”

Straight from “Married With Children”, Christina gets to play one of the three Green sisters (Jennifer Aniston, Reese Witherspoon, and Christina Applegate) and character has Emma’s ears pierced when she babysits for Rachel.