As above really, its just a corsa went past us last night and a couple of my mates wer saying that it was pretty quick coz it had been "cammed".

Can anyone explain this to me just to shed some light?

Sorry for being a retard

Nick

had a aftermarket cam fitted to it

Yep,a camshaft of different profile than standard,which opens the valves differently (timing and reach),changing the way the engine breathes. Mildly cammed could describe a profile of up to circa 285 degrees,with heavily cammed describing a post 300 or scatter.