2x21 "The One with the Bullies"

Chandler and Ross run into two bullies at the coffee shop, one of whom steals Chandler's hat. Monica, down to her last few dollars of savings, plays the stock market based solely on the ticker symbols to avoid taking a job at a tacky 1950s themed diner. Phoebe makes multiple attempts to visit her birth father, but instead she meets her half-brother, Frank Buffay Jr., and learns that her father hasn't been home for four years. Monica eventually loses her savings due to her unwise investments, and is forced to work at the Moondance Diner, dressed in a ridiculous costume and dancing on the counter to songs by The Village People.