What's grosser than gross?

Remember that old joke from grade school? I don't really remember how it went, just that one line of it, "What's grosser than gross?" Once you have kids you get the home game version of What's Grosser than Gross, free of charge, delivered directly to your home, no need to pay shipping and handling. For example...

Scene: Fiona's bedroom. Fiona and I are reading bedtime stories and getting ready to turn off the lights when I notice something dark and spotty on the wall.

Me: Fiona, what's that on your wall?
Fiona: Boogers.
Me: Boogers! Why are they on your wall?
Fiona: Because I didn't have any kleenex!
Me: Well, please don't pick your nose if you don't have something to put the boogers on.
Fiona: OK Mommy. Look they flick right off the wall! You try it Mommy.
Me: No thanks, buddy. I don't want to touch your gross boogers.
Fiona: Boogers aren't gross Mommy. They're TASTY!

Sigh....