There are things boys are just born knowing how to do. I didn't believe it until I experienced it. But it's true. Burping seems to be one of them (as well as another bodily function). We never TAUGHT him how to do these things. He just does them.
And he can do them on cue.
The other thing boys are born knowing how to do is sound effects.
I have 2 older brothers and I remember there always being fight-scenes and sound effects.
There's no audio with these pictures but can't you just imagine the gut punches, weapon swinging and falling screams?