Turbo Encabulator - The Original
This video is one of my very favorites. To non-engineer/non-Techie folks it may be a bit less funny, but for the rest of you, a "Coffee Spew/Keyboard Protect" mode is recommended before watching!!
There have been several re-do's of this, but the original is still the best. Supposedly, this was totally ad-libbed as a sound check before filming the actual promo for a new transmission. Whether or not that's true, it's still brilliant!