Welsh valleys slang. To drive around in a car (usually a clapped-out Escort/Nova covered in cheap spoilers and Max Power stickers) with your mates, wearing baseball hats, listening to an incredibly loud stereo, in an attempt to impress and then impregnate the local 14 year olds.

"allow it" means to just leave something alone, or don't worry about it. People in West London say this quite often.