The three second rule is as follows: When you walk into the room where the girl you are interested in is or when she arrives in the vicinity you must initiate conversation within three seconds so to convey spontaneous thought. If you do not follow it and initiate conversation after a couple of minutes she may be less talkative and less attracted by your likely prepared speech. Even if you come out with some shit it will likely be better than preparing something to say. She'll probably be able to tell.
*Shit here she is, here goes*.."eh Hey you're looking fine today girl..where have you been i've not seen you since yesterday"
"yeah! I was at my boyfriend's house"
"oh, ok, eh, *wtf nooo!* - eh, what u been up to then?"
The rule that says if you drop a piece of food on the floor it is ok to eat if you pick it up in three seconds. Usually the 'three seconds' is more like 10 but it is still the three second rule.
*accidentlly drops a chip*
"Three second rule!!"
The amount of time allowed for spraying deodorant or cologne such as Axe or Tag (also called TSR for short). It's the responsibility of everyone around the potential offender to monitor his usage, as excess usage of body spray has been known to render potential hookups (and really anyone) unconscious. Any breaking of the three second rule is punishable by confiscation of the offender's aerosol can and/or death. This rule also applies to aerosol cans such as Febreez and Oust if these products are used in confined conditions.
-Bro 1 sprays Axe product until visibility is reduced to that of a monsoon-
Bro 2: Dude! Three second rule!
-Bro 2 seizes can from Bro 1 and inserts the still-spraying can into Bro 1's throat-