Arnacle
an "air barnacle"; a human crustacean with a low social awareness, which attaches itself permanently to a single acquaintance in public settings. Arnacles feed by nursing a sole beverage and discussing old or irrelevant topics with their host; synonym of leech.
Guy 1: "Jason latched on to me at Emily's party on Saturday and would not stop talking about our senior year football season. Had to introduce him to Christian so he'd latch on to him instead."
Guy 2: "Damn, sounds like such an arnacle."
Guy 2: "Damn, sounds like such an arnacle."