Shark Thumb.
The sexual act of placing you little finger (pinky) inside your partners anus (butt), while keeping all other fingers tucked in except the thumb that will stand proud and looks like a shark fin just slightly cresting the bottom of your partners posterior (butt) as they lay on their front.
The sexual act of placing you little finger (pinky) inside your partners anus (butt), while keeping all other fingers tucked in except the thumb that will stand proud and looks like a shark fin just slightly cresting the bottom of your partners posterior (butt) as they lay on their front.
During foreplay Sam Shark Thumb'ed meredith last night, meredith giggled as she looked over her shoulder and saw the shark fin (Sam's thumb).
by Samqwell December 30, 2019

by Oyeboman May 14, 2011

by Daddy332769 May 20, 2021

by Xboxer September 25, 2010

by Brdmn68 May 2, 2018

When you put your thumb in someone’s ass while walking by... Like a Wet Willy but with your thumb in their butthole.
by BEANERSCHNITZEL June 6, 2018

by Balooga420 May 20, 2021
