I don't think the worlds announcers know what it means. They just heard kids saying it, and now they say it.
Clapping as a phrase come from 2 large people fucking. The waists start flopping together, and making a clap clap clap noise.
They are basically saying this person is being fucked by a fat man.
I am not offended, Im just not sure this is the calibur we want on live games.
Next they will say, Gailio just RAPED mid lane, and Jayce is absolute CANCER!
They should stay a bit professional, and saying that mid lane just clapped, is pretty trashy.