Buttbent 

Extremely perturbed or agitated.

The fact that they knew we were coming, and they made plans to be elsewhere, really makes me buttbent!

Buttbent by John Bartholomew August 25, 2021

buttrent 

As a guy, sleeping with your male landlord in lieu of money.

1. John was four weeks overdue for his rent and had no hope of finding a job, so he had to pay buttrent again.

2. Alex was mystified by the sign on his new apartment block that stated "no cards buttrent will do".

buttrent by Antimony, Duchess of Norwich November 11, 2012

Buttberty 

The point in puberty where the butt changes from a child's butt to a more shapely one.

I wasn't until Piper came out in her bicycle shorts that everyone noticed that she was going through buttberty.

Buttberty by ApricotFields June 18, 2020