The lobsterclaw is a maneuver in which the recipient is usually distracted in a bent-over position, leaving them exposed for said action. The giver of the lobsterclaw recognizes this opportunity to capitalize, and morphs their hand into the lobsterclaw itself, which is the middle and ring fingers pressed together, while the thumb roams free, resembling a lobsterclaw. The timing, brute force, and placement of the grab is what makes or breaks the lobsterclaw. Ideally, the grab is placed on the recipients taint, causing great discomfort and fright. The pressure involved is up to the giver, resulting in a direct relationship of pressure to satisfaction.
"HA! Ian totally lobsterclawed the shit out of Robert, he wasn't even expecting it."
"That lobsterclaw was EPIC bro."
"Yeah man, he was just asking for the lobsterclaw."