piston

noun

1. A solid disk or cylinder that fits inside a hollow cylinder, and moves under pressure (as in an engine) or displaces fluid (as in a pump)
2. A valve device in some brass instruments for changing the pitch

verb

1. (intransitive)To move up and down or in and out like a piston.

   “The Latino warrior fucked like a man possessed. His lean hips powered the pistoning rod in short, vicious jabs, so rapidly that the shit-streaked cock was a blur as it pounded Captain Randall's butthole, churning the screaming soldier's ass-juices, rectal blood, and smashed turds into a slimy froth.”

name

1. A surname.