Number 2 

To poop, defecate, excrete fecal matter from the anus.

I had a lot of pizza, so now I'm constipated and finding it hard to number 2

Number 2 by Walter Schwartz March 26, 2015

number 69 

Sexual meanings; Often used as a joke to say a number or answer like on a test

Lola: What's the answer to number 6?
Jake:Number 69!
Lola:U stupid little nasty motherfucker!

number 69 by Twenty1Crybaby June 4, 2017

Number One With A Bullet 

Fast moving to the top. Going all the way to number one as if attached to or accompanied by a bullet. A reference to the Billboard top 100 songs where a fast moving track was accompanied by a 'bullet' icon on the chart. Inspiration of the AC/DC lyric "Number One with a Bullet. I'm A Power Pack."

"That new Ice Cube track ain't just a number one, it's number one with a bullet!"

Number One With A Bullet by MrGomezAddams March 14, 2012

number 3 from the numberjacks 

The hottest number from the numberjacks, the real legends even had the toy.

person a: do you like anyone
person b: nah, i've been simping over number 3 from the numberjacks

number 3 from the numberjacks by Comander Erwin December 21, 2020

number 4 

Slang for heroin. AKA number four heroin. Its etymology refers to the last of a 4-step purification process in which heroin is purified into a white fluffy powder.

Aunt Hazel warned cousin Charley of the dangers of doing number 4.

number 4 by J town booga January 9, 2008

Number neighbor

Someone with same number as you but the last digit is one off.

Ex: 123-456-7891
The number neighbors would be

123-456-7890

123-456-7892

My number neighbor just texted me and he's really weird. His numer ends in 1234 and mine is 1235

Number neighbor by savvymcjay August 8, 2019

number nine 

A term frequently repeated in The Beatle's advant-garde track
Revolution 9. The significance of this line baffles musicologists to this day.

"Number nine is my favorite number because The Beatles said it a lot."

number nine by badusername99 April 28, 2010