Here's an example:
<Music plays, similar to that from a jewelry box>
<Friendly voice> Do you like ribbons and kittens and cute little cartoon characters?
<Sound of jewelry box being destroyed>
<Darker music with a heavy bass line starts>
<Same person. Evil, loud, harsh voice> Then you've come to the wrong place, Tinkerbell!
<Same person, aggressive voice still, but not yelling> Pseudopod is
the weekly horror podcast. We bring you stories from the strange to the disturbing to the downright bone chilling, cry for your mommy, don't turn off the lights horrific.
<pause>Come see us on the web at
www.pseudopod.org<back to aggressively evil>And leave your fairy dust at home.
I just did that one off the top of my head, and I didn't time it. I put this up here to show how little is actually needed to be put in a promo.