thugbutt 

Shared anal enjoyment of a double ended dildo by two participants.

Hey baby, how about you and I enjoy some hot thugbutt tonight with my new toy?

thugbutt by Kinkmeister August 30, 2013

Thumbutt 

The act of inserting one's thumb into another's butt.

The thumbutt, also known in it's original latin form, (thumbus buttus) is an ancient practice, dating back to the origins of mankind.

Yea, Jenny was being a total bitch so I just had to give her the ol' thumbutt.

Thumbutt by Dr.moopaloop June 7, 2011