A torture device of many forms and shapes. The main purpose it serves is to inflict slow and excrutiating pain to the fingers or toes of a victim.
A sexual technique involving the thumb (or both thumbs) to screw or fuck their partner or victim. Usually performed in the "thumbs up" or "handshake" position.
1: After the thumbscrew was applied to the cookie monster, he confessed to taking all my cookies.
2: "If you insert your thumb in an orfice then you are thumbscrewing."