1. The Posers:- These are cool Delhi dudes whose main aim in life is to impress  girls and would go to any extent to do so. They come to these concerts impeccably dressed up, cool glasses, hair done up using copious amounts of hair gel. To give themselves the “Rocker” look, they wear things like scarves on their elbows, bad-ass gloves, chains hanging from their pockets etc. To complete the wannabe impression, they talk loudly in fake accented English and address each others as bros/homies/fellow-rocker. Before the concert starts, they would keep shouting things like “We will rock tonight” and “Rock my brains out” etc. It need not be said that their idea of rock music ends at bands like Linkin Park, The Rasmus, Green Day etc. They are mostly accompanied by rocker chick(s) (to be covered later) whom they explain the band’s history in detail and the songs to look out for. They are also apparently friends with at least one of the band members and would try to meet him in front of his friends to prove this to them. During the performance, they would frequently break into fake air-guitaring bent backwards. Why do they do all this? So that they can update their facebook profiles with their photos from the concert so that everyone can know how cool they are.
2. The Rich:- These are men in 40s from areas like Vasant Kunj, Defence Colony, New Friend’s colony etc. They would come to a concert in their Mercs/BMWs/Jags, dressed in expensive suits with their socialite wives and crap-spoilt-fat children. They would keep checking and replying to e-mails from their smartphones (Blackberrys 2 years ago, Androids these days), “sit” at the back (so that no one steps on their expensive suede shoes) and pass the whole concert without any expression. The children would play games on their iPhones. They would  also look at distaste at the poorer crowd and leave some time before the concert gets over, so as not to mix with the poorer crowd.
3. The Clueless:- These are mostly Jats & Bhaiyas with a lot of money but no culture/class/education. They would be passing by the venue (in their open air jeep) when they would see a crowd gathered and since they have no jobs or anything else to do, would buy tickets (not without haggling) and come in. Inside they would be clueless as to what is happening and would ask young folks “Yo kay chal rahya se” . Once the band starts performing, they would laugh at the type of music being played and also laugh at the headbanging audience and say ”Inme to bhoot chadh gayo”. But since they paid money for the tickets, they would stick around till the end, abuse everyone and leave.
4. The Rocker chicks:- I should start off by saying that 99.9% of Delhi girls should not be allowed to enter rock concerts at all. They are an insult to the band as well as they fans. These are upscale Delhi girls. Their idea of being a rock-chick is to apply heavy makeup and wear small clothes (or Lady GaGa T-shirts). They would let their boyfriends (see: The Posers) haggle with everyone to let them be at the very front of the crowd, have the boyfriends (see: The Posers) bring a chair and sit and watch the concert. They would frequently ask the boyfriends (see: The Posers) to muscle their way through the crowds and bring them drinks. After drinking a little, they would dance to the solo of Comfortably Numb with their fellow rocker chicks while their boyfriends (see: The Posers) keep others away lest someone touches them and derives them of their virginity. Needless to say, the sight of such women makes my blood boil.
5. The Dopers:- These are mostly Delhi University students. They drink and dope before turning up for the concert. They have long hair (if any) and thin emancipated bodies. They are mostly dressed in black with all-star sneakers. Their favourite genre is Death Metal. The louder the music and more incomprehensible the lyrics, the happier they are and more furiously they bang their heads. Between bands, they go to the corner to smoke some more dope (hidden in their socks or underwear) and then return for some more furious headbanging. After the concert is over, they stand clueless outside the venue with no idea of how to get back home. Surprisingly, this is the least dis likable groups of all the above.

PS: Thanks to Papa tere Papa of Baytay for the Haryanvi text.