I agree with the general point, but "riding dirt bikes in the street" is possibly not as innocent as it may seem.

In rural areas riding dirt bikes on the street might conjure up images of a couple of brothers tearing around a few fields, generally making a mess but ultimately just doing it to have fun. In cities however there is often (by no means always, but often) something else going on.

At least in Philadelphia, gangs use dirt-bikes and 4-wheelers to 'patrol their turf' and flee the police (who are largely powerless to stop them, as they travel in groups of 10 or more, and all split the second a cop turns his lights on). In these instances it isn't harmless fun, they are basically neo-'biker gangs'. It is a big problem in north and west Philadelphia.