There are a few conventions that seem to be adopted so quickly that no one notices that they are new; but just become part of the furniture; for instance
1. The phrase “for sure”…where the hell has this come from?
2. Using “I’m sorry” as a synonym for “excuse me,….”, or calling for a stranger’s attention
3. Fashionable pop-up words that just suddenly people use; for instance “panic buy” (in light of the recent economy situation); or “sexed up”, from the phrase “sexed up dossier” referring to the Hutton Report.
I’m a bit old to really understand youth culture (sadly, I must say…); and I notice very odd conventions that seem so entrenched, so quickly into our public discourse, that only not saying them makes it to be shown.
I’ve not even started with internet informal comminiques; I was at a dinner party once and a lady said “‘lol”; not ‘laugh out loud’, but the phonetic lol.