The j that is also the main one. A common nickname for Jonathan. Usually used in cases where the Jonathan is a loser and/or a person with miniscule genitals. Jmain is the supreme overlord of the losers. He has ultimate control over anyone with no friends. His miniature member gives him the power of rape hypnosis.
That guy is gross! He's such a Jmain!
by TheSecretNipple February 28, 2013