I saw AuvaAkita's comment parodying "London Bridge is Falling Down", and decided to write a whole version of it! I'm not set on the lyrics, so if you want to change them go ahead!
Here is the original if you want to compare them: http://www.zelo.com/family/nursery/london.asp
For added fun, change the word "lady" to Rick!

♪ The whole world is falling down, falling down, falling down. The whole world is falling down, my fair lady. ♪
♪ Take a key and lock Keene up, lock Keene up, lock Keene up. Take a key and lock Keene up, my fair Lady. ♪
♪ How will Rick build the plot, build the plot, build the plot? How will Rick build the plot, my fair lady? ♪
♪ He'll build it up with silver and gold, silver and gold, silver and gold. He'll build it up with silver and gold, my fair lady. ♪
♪ Plots so good they must be fun, must be fun, must be fun. Plots so good they must be fun, my fair lady. ♪
♪ He'll leave us on needles and pins, needles and pins, needles and pins. He'll leave us on needles and pins, my fair lady. ♪
♪ Twists so good the world will shake, world will shake, world will shake. Twists so good the world will shake, my fair lady. ♪
♪ When there's an update we shout hooray, shout hooray, shout hooray. When there's an update we shout hooray, my fair lady. ♪
♪ There are cool characters like The Great Kitsune, Great Kitsune, Great Kitsune. There are cool characters like the Great Kitsune, my fair lady. ♪
♪ Build the fandom up so strong, up so strong, up so strong. Build the fandom up so strong, my fair lady. ♪
♪ We hope Housepets! will last for long, last for long, last for long. We hope Housepets! will last for long, my fair lady. ♪

I don't mean to offend you but personally I think the lyrics are too simple, they don't make me laugh or provoke my interest. I think you could've done less repetition and completely change most of the lyrics so it tells a much more diverse story. Think about the Joker's take on this song.

"Big old bat's is falling down, on the ground, what a sound, big old bat's is falling down, i'm so happy!!!"

I agree, but it is a very good idea, with good-ish lyrics.

It's ok, I never claimed to be a song writer. I just put what came into my head at the time of writing. I really put this here so people could help me build it into something better, cause I agree it could be a lot better. So please suggest some new lines and I will edit the original if it's good!