People always say Hollywood is a lot like high school, and when you see how many celebrities have dated each other throughout the years, you start to realize how true that is. From Kim Kardashian and Nick Cannon to Britney Spears and Colin Farrell (wait, what?!) — it's no surprise we have a hard time keeping up.

MUST SEE: Jennifer Aniston, Ryan Reynolds, and More Stars Reveal Their Awkward First Dates With Other Celebs

Click through the gallery to see celebrity couples you forgot used to date.