"He a G"
Internet meaning: Boxer in question is a proper dickhead with a vile personality who generally acts like a cunt, and the poster who called him "G" has poor english skills.
"He's a proper character he is"
Real meaning: Someone who is funny, charismatic, tells interesting stories and is fun to be around.
Internet meaning: Someone who slaps, bites, spits, has convictions for public order offences, acts like a cunt, and when punished for said behavior proceeds to complain and make threats in a horrendous accent.