This prom took place in Monica and Rachel's senior year.
Ross ran upstairs and went to put on his father's tuxedo and just as he was about to ask Rachel, Chip had shown up already and all 4 students left, stalking out the door. Ross was left rejected and heartbroken.
At the prom, Rachel couldn't find Chip for 2 hours; he was having sex with Amy Welsh.
In The One With The Prom Video, the preparation was recorded and when Rachel saw that Ross intended to go with her as her replacement date, she forgave him for a list he wrote about her and his ex-girlfriend Julie and they started a relationship.