Totally with you on 'chav', but I don't think 'cager' and 'mansplaining' are in the same category, because in both cases they're words used about members of dominant groups by members of less-powerful groups (as a driver, I find 'cager' kind of rude, but that's partly the point of it, although of course I'm also a cyclist so probably not best placed to judge).

Mansplaining doesn't actually mean 'offering advice instead of sympathy', it means being a man offering patronising advice which assumes the female recipient of said advice is stupid and in need of your greater wisdom, and it's more usually done by acquaintances or strangers than friends - there's an implication of overstepping bounds in offering advice at all. It's a label for a rude behaviour, not for someone who is genuinely and politely trying to help but doing so misguidedly.