The Disco Smile occurs when someone cranks the BASS and TREBLE way up on their stereo system's equalizer, leaving the mid range very low. On a graphic equalizer, this curve will look like a mouth smiling.
You have now achieved the disco smile. Good job, I hope you didn't *really* want to hear everything that song had to offer.
Lauren: Hey Chris, turn on your car stereo!
Chris: Okay! *click*
Lauren: ARG! Why are my ears bleeding, and I still can't even tell what song it is? Oh, that's right, you're a fan of the disco smile.
Being exceptionally excited about something. Saying, "I'm excited about this," only says so much and can be taken in so many ways, but if you say, "this has me shitting kittens," there is no contesting the level of awesomeness that must be awaited.
Scammon: You excited to see Mr. Bungle tonight?
Noah: You kidding me? I'm shitting kittens!