Those little "Excitations" heard in the background
 

You hear it every now and again, somebody either in the band or the producer or some hangers-on just getting into the moment of a song and letting out with a little yeah! or a little whoo! that you hear in the background.

One example that I've been able to pick up on:

Making Love Out of Nothing At All by Air Supply
Heard twice, once in the middle and once towards the end. Might be Jim Steinman, the producer and writer of the song, getting all into it.

There are others, but I can't remember at the moment.

You should pick up a Glenn Gould CD sometime.

Moments like these seem a lot more common in jazz as opposed to anything else I listen to. Art Blakey was known to let out some yelps on his albums, and I'm sure there's thousands of others. I like hearing stuff like that.

Heard a little yeah! in Kyrie, just before the 2nd verse.

Do you mean like Gary Glitter's Rock and Roll Part I?
:D