Guest leech
A guest leech is a person who tries to suck guestlists like a leech sucks blood. Guest leeches are dangerous parasites that will not hesitate to manipulate in order to obtain a few show tickets or backstage access.
Mathieu: Jessica has been texting me all night for guestlist tickets...
Charlie: Yeah I know, she's such a guest leech!
Charlie: Yeah I know, she's such a guest leech!