I have noticed the expressions 'Music 101' and 'History 101' used (obviously satirically) on the SE26 forum recently. I was puzzled, but research suggests that the number '101' is used in American universities to refer to the first (and therefore most basic and elementary) courses or modules in a particular subject as taught to undergraduates. Has this usage become widespread here? Or is it just that it has featured e.g. in some popular TV programme or something similar and therefore become suddenly fashionable amongst the young and 'switched on'?