A Cowboy's Dozen 

to buy as much of a desired product as one can afford with the amount of money one is carrying.

Cashier: Can I help you?
Customer: I’ll take some of those one dollar scratch-off tickets right there.
Cashier: Sure, how many would you like?
Customer: A Cowboy's Dozen (throws money on counter)
Cashier: (counts money) Soooo, seven then?
Customer: I reckon.
Cashier: Good luck!

Could also be used to exaggerate a story:
Derek: How much money did he say he won on that bet?
Jeff: A Cowboy’s $300.
Derek: Meaning?
Jeff: $200

A Cowboy's Dozen by iBetty January 10, 2012

cowboy's secretary 

when the girl is riding you, your phone rings, and she picks the phone up and answers it without getting off or taking it out.

last night when you called and my girlfriend answered, we were actually doing the cowboy's secretary.

cowboy's secretary by The Cowboy with The Secretary April 25, 2011

Cowboy's Dinner 

The act of furiously jerking off while throwing up into a toilet.

"Just walked in on Matt making a cowboy's dinner."

"I don't know what I drank last night, but I woke up in the bathroom with a Cowboy's Dinner infront of me"

Cowboy's Dinner by robohobo_ March 18, 2017

Cowboy's handshake 

A game in which you grip the other person's hand as hard as possible in the form of a handshake. Whoever loses grip first will get their hand crushed, after which the winner loosens their grip. (Play at your own risk)

I did a cowboy's handshake with John and my hand still hurts like hell

Cowboy's handshake by Just Jesus Christ January 27, 2021

rootin tootin cowboy shootin 2

rootin tootin cowboy shootin 2 is just a better version of Red Dead Redemption 2

Let's play some rootin tootin cowboy shootin 2

rootin tootin cowboy shootin 2 by ⒾⓐⓜⓈⓄⓊⓅ December 28, 2018

Cowboy Stop 

When that stupid cop pulled over polecat324.

Polecat: What is the promblem officer.
Cop: You Cowboy stopped.
Polecat: Da fuck is that?

Cowboy Stop by Green ass alien June 18, 2019

Cowboy shit 

To be doing any activity in the same vein as the old pioneers of the 1800s. Usually by being stupid,reckless or dangerous though most of the time all three.

Man #1 "That mf Skiing down mt everest is suicidal!"
Man #2 "Nah bra he on some cowboy shit"

Cowboy shit by BIG HERCS BIG UNCLE March 9, 2021