73 

Sheldon Coopers favourite number
He likes it because 73 is the 21st prime number with it's mirror 37, which is the 12th and it's mirror which is 21 and is the answer to 7x3.
He likes it most because 73 is a palindrome (1001001).

73 fans: "I think 73 is the best because I'm a nerd"

Leonard: "73 is the Chuck Norris of numbers"
Sheldon: "No it's not, all you get from Chuck Norris backwards is Sirron Kcuhc"

73 by My name stays private :) December 5, 2013

73 

ham radio talk for "best regards" or "talk to you later", "good bye for now". Originated during the early days of radio where abbreviations shortened messages in Morse Code.

- - ... ... - -

"73 de W1AW" = "talk to you again soon, from radio station call sign W1AW"

73 by Rod C. December 10, 2003

73 

69, with 4 fingers

I gave that bitch a 73

73 by Anonymous July 19, 2006

73 

The most amazing sexual position ever! One couldn't even compare it to 69 or even the lazy dog!! It's simple enough, just get your unconscious victim... er willing partner to lie on the their stomach and place your "candy" on top of their "jiggle mountain". Relax and enjoy

Caren: Ughh... Mike left semen crusties all over my left cheek from 73ing last night

Aaron: I have some from Mike too... at least it was fun

Caren: That's for true :] way better than 69ing

Aaron: Or even the lazy dog!

73 by 73 addict May 3, 2009

73 

73 is a number after 72 and before 74

I am 73 years old fart

73 by harrymonkidiopathic September 3, 2020

“73”

A fictional score O’Leary claims to have shot in a tournement he cheated in

Did you hear after O’Leary’s “73” he shot 49 on the front and 51 on the back with a 10 on hole 17?

“73” by CheaterBCC July 8, 2019

73-9 

a telephone number that does not ring when receiving calls

I am trying to call 73-9, but there's no ring

73-9 by Unicornication July 2, 2016