Quoting applelove:" This is normal just less comon. My baby was walking at 9 months so yours might start walking soon. Some ... [snip!] ... becuase they like to make you happy. This might just be what your babie likes todo and I am sure walking will come soon enough."
Well I'm not sure about the laughing because we kinda just let him do his own thing when he's playing on the floor. But I've noticed he will roll more if he sees the dog. It's like he HAS to get to her right away. But yea that's true I guess what the previous poster said. He probably just figures he can get around that way so why stop lol.