Conversation with Buttercup while on the swings the other day:
Buttercup: Do you know how you get boogers?
B: It's dirt and dust in your nose.
M: Really! Then whats the slimy stuff in your nose?
B: It's snot!
M: How do you get snot in your nose?
B: It's smashed boogers. You smell yummy smells and the boogers don't like it and they get smashed. That's how you get snot.
M: Oh, Thanks.