What do you call Santa's fear of being stuck in chimneys?

Claus-trophobia.

What's the hardest part about celebrating the "Twelve Days of Christmas" in an apartment?

Trying to find enough room for twelve drummers drumming, let alone a partridge in a pear tree!

What did the Christmas tree say to the Christmas tree decorator?

You're always stringing me along, but I'm pining for a simpler look this year.

Why did Santa invest in a new filing system?

He wanted to keep track of all his Clauses.