A 'Crockstar' is someone who says they are seriously into rock music, but will only listen to obvious bands. They will usually tell you that they are "not really into" or have "never heard of" the likes of.. Maiden, Dream Theater and Def Leppard. These same people, if asked, would not be able to tell you the track listings for Led Zeppelin IV or Master of Puppets, if their lives depended on it. This is embarrassing, they are not seriously into rock music, and so they ought to stop telling people that they wish to live a rock 'n' roll lifestyle, cover their body in tattoos and learn to play the guitar like Kirk Hammett, because they will only humiliate themselves further.
Crockstar: "Hey man, I'm going to Download this year!"
Guy: "Really? I hear Faith No More and Dragonforce are headlining!"
Crockstar: "... Who?"
A inconsequential person who talks a big game, but their big talk is just a crock of shit because they never do what they say they will.
"Crockstar" is the antonym to, and should not be confused with a "Rockstar".
That guy is such a crockstar. Time after time, he has offered to things and then always has an excuse to offer, but no results.