CULOM

An abbreviation for See You Later, Old Man.

Commonly used especially in radio communications scenarios, especially in teleprinter/teletype communication, as a signing off abbreviation when some operators are chatting together during setup or closedown or any other time when the system isn't in used for real messages.
CULOM is one of the ancestors of webby words such as ROFLMAO, YMMV etc. and itself is one of the descendants of TTFN, ROMFT etc.