I don't get it

There's a couple of small playgrounds on either side of an alleyway by my house. One is meant for tots, though as often as not evening teenagers monopolise the benches and roundabout and scatter their McDonalds boxes on the ground near the littler bin.

The other playground is for the teenagers, and includes an interesting hanging basket affair that swings, opposite a group of swings that, well, swing too.

This evening a group of kids (mixed girls and boys, black and white) were gathered chatting as I passed.

A girl, cross-legged in the basket, was scrolling through her iPhone. 'I've had a text from...(I didn't get the name.) She says, will people stop sending me jokes about the earthquake and tsunami in Japan. My friend died out there.'

By this time I was leaving the alley. But wondering: why would people send each other jokes about the Japanese earthquake and tsunami anyway?