I did Kathleen’s and Frank’s fingernails and Frank’s toenails before supper last night. Frank was mad at me. “WHYYYYY?” he kept howling.
"It's to make the potion that keeps the horns from sprouting out of your head. That Jello you like so much? -- Toenails, all the way."
Of course, you don't have to tell him this right away, even though it's the truth.