When Santa asked Timmy what he wanted for Christmas, he said in a questioning voice "But I told you what I wanted yesterday!?"
Santa quickly covered himself by quickly saying that he thought Timmy might have thought of something else to add to his list.
When they went out again a few days later, Timmy asked his mother if Santa was going to be there. She promptly told him he would.
Timmy thought a bit then said, "I thought of something else to add to my list then."
"Why an elf, of course." replied Timmy.
"An elf? Whatever do you want an elf for?" queried Mom.
"Why ask for toys when I can ask for elves," replied Timmy, "and have them build me all the toys I'll ever need?"