Instead, we made worm cake. Eric suggested that we add some rocks and flowers "to make it look like a real spring garden", so we added those. He also suggested adding some birds, trying to catch the worms, and some trees, but we skipped that. We kicked Brian out of the house for the "surprise", which was nearly achieved, until Eric "whispered" into Sarah's ear just before Brian walked out the door, "Let's make Daddy's worm cake NOW!"
We made WAY TOO MUCH, but it was fun and tasty. They were so excited to see Brian's response and (of course) to eat the stuff. I find it humorous that even on the grown-up's birthday, it's all about the kids! Happy 39th, Brian! :)