It's a mystery.

Just when did this vogue for applauding yourself start and why?  It seems to be the done thing more and more these days - you see it particularly on game shows, when a contestant gets a correct answer, and the audience claps them and then you see them clapping as well!  The first time I remember consciously seeing it was on TV way back when Nikita Khrushchev was the Soviet premier and was introduced at some shindig or other and responded to the applause of the crowd by applauding himself, and I remember thinking - what the...?  What I can't understand is who are they applauding?  Themselves (what a big head), those who are applauding them (what's the point)  or what?  Anybody got any thoughts?