ie) Someone who merely acts like a friend but has a constant hidden agenda. A friend who is ungenuine would likely not keep in touch over a period of time only to hit you up out of the blue because it turns out they actually need something from you.
Ungenuine can also be used to describe someone who treats women with disrespect, fools around with multiple women in a given sitting at a given location (usually an aggressive type), untrustworthy, is overly sensitive about jokes, and is otherwise not a person who the rest of the group is fond of.
2. "Don't invite Tony to your kegger, he's so ungenuine.. He never pitches to bring any booze and always invites like 50 randos.."
3. "My bunk-mate came home last night with a girl, woke me up and tried to kick me out of the room so he could bang her on the bottom bunk.. That guy is such an ungenuine POS."