1) A person in a gang that is mentally retarded
2) A person in a gang who thinks they are better than all the other gang members but in reality are actually out of style.
A nerd that tags along with popular kids would be a Gangtard.
1) One who is Mentally Handicapped yet dresses like a complete douchebag; It's okay though. They're retarded hence the definition, Gangtard.
2) One who is normal yet dresses like a complete douchebag; It's not okay. Have common sense.
Jackass: "Haha! Look at the retard thats dressed like a Douchebag!!"
Nice Person: "Hey! Don't laugh! He's a Gangtard! He doesn't know any better!"
Jackass: "Dude, check my new jersey, its cut off at the sides to show the world my red hot nipples."
Normal Person: "Dumbass. You're such a Gangtard"