1.) Your
man. Or, your friend.
2.) Often times
someone you "back" or "represent".
3.) This can also be you, referring to yourself in the 3rd person.
4.) This term can also be used in a derogatory sense, but in a
sarcastic and often humorous way.
"Holler at Jerboi. He's the one bringing over the beers."
"I'm not sure Jerboi is handling his shit these days. I
seen him maxing on some serious ho-ology at the
bar last night"
"Jerboi is blowing it."
"Get at Jerboi, I told you I was feeling you already
girl"