look up any word, like ratchet:
 
3.
simply the greatest three words you'll ever hear. the magic password to quickly get you out of any situation.
must be accompanied with a twisted right leg kick across the left leg as the left arm comes twisting across the body in a punching motion. when performed correctly, everyone will know it.
1. b: did you see that guys leg kick?
j: you KNOW it!

2. b: did chuck norris just get eaten by david hasselhoff?
j: you KNOW it!

3: g: is that a herpes bump?
j: you KNOW it!
by brianisgay January 20, 2006
 
1.
Said in agreement to a statement or question. See word
-Thats a massive spliff you just rolled
-You know it
by Stoner 04231 November 25, 2003
 
2.
used when recieving a compliment or a praise

a confident catch phrase
Guy : "damn girl you lookin good today!"
Girl: "You know it!"

by samerin June 07, 2006
 
4.
a euphemism: it is an indirect, quasi-sensible answer to any question.
Pamela: yo, Dolly have you seen "Final Destination 5" yet?

Dolly: you know it
by JessieJackson124 November 13, 2012
 
5.
Originally coined by Frank The Tank (Will Ferrell) in the movie Old School, this phrase is now running rampant in college campuses across America. Can be said in agreement to a statement, or in answer to a question. Also at random times if you're bored.
1: F: Awesome... YES! I am back. Woo! You KNOW it!

2: A: This Karkov tastes really good.
J: You know it!

3: D: Dude, did you just pass me in Mario kart?
B: You know it!

4: J: God I'm wasted... YOU KNOW IT!
by JK February 08, 2005
 
6.
To totally disregard what someone is saying or said, and just agree with them completely whether or not they're right.
Example 1

Guy A : Sometimes I wonder if I should even be alive...
Guy B : You know it!

Example 2

Wife : Honey, I'm pregnant, and I don't think it's yours..
Husband : You know it!

Example 3

Guy A : Should I get a...
Guy B : You know it!
Guy A : But you didn't even let me finish...
Guy B : You know it!
by Jorge, aka Nimbo October 27, 2008