1)A person who is likes an EXTREMELY LARGE amount of semen for the pleasure of getting cock all the time.
2) Or a girl you want to have sexual relations with to the extent that you coat her in a thick layer of semen.
1) Dude I hope you choke on some guys dick you Jizz Rooster
2)That girl is so hot I am going to make her my Jizz Rooster tonight.