Thumb Butter 

When your wiping yourself and your thumb accidentally breaks through the toilet paper and gets "dirty".

Dude! I dropped the kids off at the pool last night and got covered in thumb butter when I was wiping with that cheap paper my wife buys!

Awww man that is the worse!

Thumb Butter by minuccp May 1, 2009

Butter Thumb 

A flaccid, shriveled, post-coitus, penis and is still moist and shiny from the amalgam of sexual juices.

After Roger tapped his girlfriend during a lunch time quickie. Sonja went to the bathroom to wash up and grab a doddle rag to come back and wipe off Roger's Butter Thumb.

Butter Thumb by Eaton Holgoode May 19, 2015