Christmas tree = C = chrome

Christmas tree packet n.

A packet with every single option set for whatever protocol is in use. See kamikaze packet, Chernobyl packet. (The term doubtless derives from a fanciful image of each little option bit being represented by a different-colored light bulb, all turned on.) Compare Godzillagram.

--The Jargon File version 4.3.1, ed. ESR, autonoded by rescdsk.