my favorite tactic is to either

a) if the dnb record is playing at 45, throw on a techno record, tick it up to 45, and start cutting back and forth. then at the right moment, hit 33 on both cuts, dropping the tech record to the right speed, and turning the dnb in to electro. THAT gets their attention.

or

b) start cutting up the dnb record and throwing delay effects on to cut up the beat. let them know right from the start that you. mean. business.