Stinky Finger: Crazy Party at the House of Fun by Jon Blake
It is December, and Stinky and friends hit on the idea of inviting everyone they know to the House of Fun for Christmas. Since the Spoonheads have sucked up all the adults into their space zoo, the three great mates are free to have the craziest party the world has ever seen. They invite all their friends.
At this point the Brain Drain arrives. Created by the Spoonheads, the Brain Drain is rather like a Blood Bank, except it siphons out a small (unimportant) portion of each donor's brain in order to revitalise Blue Soup. This is the first time since the Spoonheads' departure that the Brain Drain has visited.
Icky, Stinky and Bryan all give brains. Next day, replies start arriving from their invitations. They are delighted, until they realize they can no longer remember what Christmas is. The Brain Drain has evidently malfunctioned ...