Thats pretty funny, I had a rat named Houdini also. He was the male to my breeding rats when I was raising them for food for my Owls. He came and went as he pleased.. I had cages from the zoo that they used to raise feeder rats and mice in, but that didn't matter. I was never able to keep him in. he would come back to eat and he would break into each females cage at the appropriate time. He would also come when I called him although I never knew what direction he would come from. I kept the rats in an old boiler house and he lived like that for 4 years.