The common courtesy of waiting roughly 5 minutes for a friend to respond after commenting on or "liking" a status on Facebook. If the friend doesn't respond within this grace period, one can assume they're offline or simply disinterested in your post.
Mom: "Katrina, it's 3:30am! Get off the damn computer and get some sleep."
Katrina: "Give me a second, I'm waiting for Jessica to write on my wall. I "liked" her status 4 minutes ago. I gotta wait for the 5-minute Rule."
Mom: "You don't have any friends...so stop pretending! And switch the damn laundry before you go to bed."
The prefix "Ja" means Candy Ass Bitch and "Rule" means Poser Geek. Case and point can be seen in that weak ass video of when he and Bennifer did the VMA's.
"Man, did you see Ja Rule pretend he was hard in that queer ass movie, he really pulled a "Ja Rule".
"Did you see that man with that teeny dick? Man... his parents really "Ja Ruled" him with their genes.
A sith law making it so that there can never be more than two active sith at one time, one master, and one pupil. The rule was set in place by Darth Bane after he killed all the other sith.(Darth bane also started the tradition of prefixing sith names with "darth")
Darth Sideous only ever had one deciple at a time, first Darth Maul, then Darth Tyranus, then Darth Vader. Although he surounded himself with other Dark Jedi, there were only ever two Sith at one time, in accordance with the Rule Of Two.
The time that a party really "begins", no matter what scheduled time the party was actually supposed to start previous. This is the time that, without fail, droves of people show up all at once and a party can go from almost non-existent to full-fledged rager.
"Man, this party was so lame for like the past 3 hours, now it's insane! (Looking down at watch, seeing it's around 11 PM) 11 O'Clock Rule, happens every time!"