When one partner is performing oral sex on their knees with the recipient in a standing position. The 'performer' then closes one hand in a thumbs-up position and inserts the full length of the thumb into the partner's rectum. Giving the in-and-out motion reminiscent of a hitch-hiker.
"Sally sucked my cock last night and gave me the ol' Flemish hitch-hiker, my ass is still sore!"
by Cpt. Slappy May 20, 2009