facebook thumb - The thumb you use to be a total prick on Facebook. It's like

The thumb you use to be a total prick on Facebook. It's like saying, 'I don't care, and I'm not even trying.'

Your teacher: "You'll pass." (you send a Facebook thumb)

Your friend's mom: "I'm fine." (you send a Facebook thumb)

Your crush's crush: "They're perfect." (you send a Facebook thumb)