Social rule that states that every group of hot girls numbering two or more must have at least one immensely fat friend with them at all times to make them look better and to provide cock blocks when necessary; usually requires a wingman to jump on the grenade. All groups of hot girls run with at least one fat girl to throw out cock blocks when needed.
-Dude we were hitting on this group of hot girl lastnight at the bar but we got cock blocked.
---What happened man, boyfriend?
-No man, The Rule of Fat Chicks dude.
---What happened man, boyfriend?
-No man, The Rule of Fat Chicks dude.
by YoungZ July 11, 2006