I opened the box and here was a cake saying "Happy Birthday Harold." We had a good laugh and ate it anyway. The next day I called the bakery, and the manager informed me that "Harold thought your cake was delicious." 

Oh, that's classic!
The funniest thing I've ever seen on a cake was done at someone's 50th birthday party. The person throwing the party got a pack of figures called "Horrified B-Movie Victims".

They look like the crowds of people running from monsters or aliens from a bad sci-fi movie.
Well, when the cake came out, it had a big "50" on it, and the host placed the horrified figures around the 50. It was priceless.
Here's a pic I found of the figures. It should give you an idea of what the cake looked like.
