Any made-up illness used to get sick days around the holiday season.
Elf 1: Man, it sucks that Christmas is in the middle of the week this year. I don't want to have to take vacation days just to travel.
Elf 2: Just call in with a case of the jingle shingles.
Elf 1: Nah man, you need a doctor's note. I'll have a better chance using holly jolly herpes.