3rd rule 

If you're gonna have sex don't forget to protect! Ain't nobody got time for babies

Duuuuude, you're gonna get laid? Don't forget the 3rd rule man, you feel me?

3rd rule by Watchagonnado June 1, 2014

3rd Date Rule 

The rule amongst honorable men of certain western cultures (New England Boarding Schools) which states that a human and his or her partner must go out on exactly three dates before being formally considered a couple. If the possible couple-to-be has gone out on three dates, still unsure of if they wish to be formally considered a couple or not, the 3rd Date Rule dictates that the pair must make their decision then. Finally, the 3rd date rule states that an honorable person does not ask the same partner on three dates in a row without intention to belong to them and them alone or can otherwise be considered to be “leading them on.”

Guy 1; Hey man, I don't know when to ask this girl when to like, be my gilfriend so we are officialy going out. What is the custom as to when I should do that?
Guy 2; ...3rd Date Rule!

3rd Date Rule by Gunter McLean May 1, 2008