If I had to pick a favourite out of all the shows I have worked on, this would be it. This show had everything you could ever want in a kids program, from farting swaps to giant robots. There was enough creatures, kingdoms, underground worlds and places to make one of those "Field guide" books.
It is basically a kid finds a secret passage under his bed to a weird world where he is king and does whatever he can dream up. He soon learns of other kingdoms in the land of Under that want his kingdom for themselves and has to defend it with his weird friends who live here. There is also many other adventure that happen during his reign, like trips to space, stopping the next ice age, fighting the pickle zombie invasion and even had to keep the land of Under from splitting in two.
It ran on the "Family channel" for a number of year ,but I am not sure exactly who else picked it up. I watched every time I could and have them all on VHS since it has never been put on DVD, but I"m still hoping.