Why do people...

...wear earphones and think that the sound won't possibly be heard by anybody else. Then turn the sound up until everybody actually can, quite clearly, hear them.
Worse: they then tap along in time or (gosh) even start singing a bit.

There was one girl (at least I think what was under the dreads was a girl) in the hostel common room listening to music yesterday while she used a computer.

Right now, there's an older gentleman doing the listening, tapping, almost singing thing. Only thing is he's not very good at keeping the tapping in time. However, to give him credit, he is listening to Dylan who's not exactly known for keeping things like timing and pitch pure.