I've posted this .wav to alt.binaries.beavis-n-butthead. It's not the full speech, as Buzzcut says a few lines explaining how B and B aren't allowed to laugh anymore. The .wav goes something like this... We're gonna be talking about the PENIS. We'll be talking about the VAGINA. Do you think that's funny, Butthead? Do you find it amusing that we'll be talking about the TESTICLES? Yes, we're also gonna be talking about VENEREAL DISEASE, SEXUAL INTERCOURSE, and... and we will definitely be spending a lot of time talking about MASTURBATION.
All this is accompanied by B and B trying to stop themselves laughing.