A sits on my lap and lets a big one rip.

Me: Ewwwww!
A: It's a natural process, Mama. Everybody does it.
Me: But not ON me!
A: (maniacal laughter)

A started singing a song in the car, "I've got a snack in my pocket...." This went on for a while and W joined in singing about various snacks.

W suddenly farted really loud and A immediately switched the lyrics to, "she's got a fart in her pocket..."