I don't get it at all even with all the hints
I got the answer thanks to @daringred_ but could someone still explain it in more details for such ignorants like me?
They are names from a deck of cards. 
Ace the bird is the "ace" card (often "1")
Elvis is the "king" of rock
Quinn sounds like "queen"
The remaining card is therefore "jack"
Ace, King, Queen and Jack are all "picture cards" in a deck of cards (and also 4/5ths of a royal flush).

Ace the bird is the "ace" card (often "1")
Elvis is the "king" of rock
Quinn sounds like "queen"
The remaining card is therefore "jack"
Ace, King, Queen and Jack are all "picture cards" in a deck of cards (and also 4/5ths of a royal flush).