To "like" something on facebook. Telling someone that you like something doesn't necessairly mean that you liked it on the book, but saying "I thumbed that" doesn't need clarification.
Dude, I thumbed that last night
He obviously posted that thinking that everyone would thumb it. They didn't. What a bad athumbtion.
She thumbed everything on my wall. It was a freakin thumbderstorm!
damn you people who dont know what a thumb is...a thumb is a FINGER, it is also a DIGIT as well as all of your other fingers/digits, they are all the same...i find it sad that all of you losers dont know what a damn thumb is...wow!