The unwritten but universally accepted amount of time before a close friend of a friend may get together with said person's ex girlfriend. It may be wise to consult close friend for approval before delving into said ex-girlfriend.
A: Hey, lets break up.
B: Okay.
*Insert Three Month Rule*
C: Hey, I'm B's friend. Wanna bang?
A: Sure.
B: Okay.
*Insert Three Month Rule*
C: Hey, I'm B's friend. Wanna bang?
A: Sure.
by Michael Habic June 10, 2008
Get the Three Month Rulemug. The unwritten rule of music (mostly but not exclusively metal) that states that only Iron Maiden are allowed to wear their own band shirts on stage, by virtue of being Iron Maiden. It has been broken numerous times. The worst offenders are probably Amon Amarth, who wear their own merchandise in every photo and every video in which they aren't shirtless.
The reason for the rule is the same reason why it's generally gauche to wear a band shirt for the band you're going to see: band shirts are generally a way to broadcast your tastes and in so doing support a band that people might not have heard of.
The reason for the rule is the same reason why it's generally gauche to wear a band shirt for the band you're going to see: band shirts are generally a way to broadcast your tastes and in so doing support a band that people might not have heard of.
by The music definitions guy December 4, 2010
Get the The Iron Maiden Rulemug. 
"Yay," Harry raised his fist in the air. "Let's go have a drunken house party."
"Harry," Sirius interjected a voice of reason. "You're in first year, you can't get drunk."
"Rule 47-5" Harry replied smugly.
"Oh . . . right," Sirius nodded. "Never mind, you can get drunk."
"Yay," Harry and Sirius rushed out of the room.
"Harry," Sirius interjected a voice of reason. "You're in first year, you can't get drunk."
"Rule 47-5" Harry replied smugly.
"Oh . . . right," Sirius nodded. "Never mind, you can get drunk."
"Yay," Harry and Sirius rushed out of the room.
by That guy over there flapping April 3, 2011
Get the rule 47-5mug. It is not socially acceptable to go out with anyone within the three year age bracket. This only applies if the younger of the two is 14-16 years old.
"Hey dude, i'm dating this chick who's 15"
"Wtf dude you're like 18, ever heard of the three year rule"
"Wtf dude you're like 18, ever heard of the three year rule"
by AnalBlaster5000 May 8, 2014
Get the Three Year Rulemug. Rules 1-36 should be the only excepted rules of the internet, as rules 37+ start to devolve into mindless, unfunny, repeated, and contradictory bullshit.
by HipstaSquirrel November 1, 2016
Get the Rules 1-36mug. A series of statistics describing the demographics of the male population at New York University. The Three-Thirds Rule states that one-third of the male population is gay, one-third is taken, and one-third is comprised of douchebags.
Chelsea: Hey, those three guys are totally hot!
Carla: Forget it, Chelsea. They go to NYU.
Chelsea: You think the three-thirds rule applies to them?
Carla: They're all wearing popped polo shirts and making out with each other when their girlfriends leave the room, so... yeah, I'm pretty sure.
Chelsea: Dammit!
Carla: Forget it, Chelsea. They go to NYU.
Chelsea: You think the three-thirds rule applies to them?
Carla: They're all wearing popped polo shirts and making out with each other when their girlfriends leave the room, so... yeah, I'm pretty sure.
Chelsea: Dammit!
by placidorgasm December 27, 2010
Get the three-thirds rulemug.