going cowboy 

Going against the rules or set of norms. Breaking the mold, usually in a spirited or rebellious manner. Similar to "going rogue". Often times reckless or careless in their pursuits.

"Why do we have so many office supplies? 2000 red pens? 500 boxes of staples? We only have 10 employees!"
"Bob from accounting must be going cowboy with the credit card again."

going cowboy by Pappa Wayne May 23, 2019

going cowboy 

the practice of not wearing underwear under one's outer clothing. also referred to as "going commando."

I'm so behind on laundry that I am going cowboy today.

going cowboy by mem13 July 1, 2008

Going cowboy 

Pushing through a task with little to no regard for your own well being or that of others.

Jack went cowboy and got the job done, pissed people off and broke a couple of ribs doing it though.Going cowboy isn’t for the weak of mind.

Going cowboy by Outlaw78a February 5, 2020

going cowboy 

To deliberately kill a number of random bystanders while performing a criminal or political assassination. It gets the message across that you really wanted the person

dead. The target was known to frequent a certain bar, so they went cowboy on the place and took him out.

The target was known to frequent a certain bar, so they killed him by going cowboy on the place.

going cowboy by man with titties January 5, 2017