Telgasm is the act of bringing a girl to orgasm using only a spadeshovel, cough drop, a door frame, and a telephone pole. Usually a dangerous task that should only be attempted by trained professionals.
Somebody who smokes pot (or any other illeagal drug) with their friends and then goes and tells a teacher that his friends smocked pot even though you did to.
Dude, you are such a telgoer, you know damn well that you smokedpot with us.