DJs spend a lot of time searching through records and scouring downloadable music on the internet in order to bring the very best music they can to the dancefloor. It's a point of pride that sets are often carefully selected, sequences of tunes crafted to bring the crowd the best listening experience possible. Requests from the audience are rarely, if ever, taken on board by a DJ, and for good reason - more often than not the request is completely out of touch with the music being played (if you think gabba is suitable for a house music set then you should probably be in a different club), while the assumption that DJs keep copies of every tune under the sun on the off chance some drunk person might want to listen to it is a ridiculous one which, sadly, some clubbers cling to. If you want to listen to your favourite tunes get your own decks or wait until you get home - the DJ isn't going to oblige.