name of the RV
Bob Munro: Welcome aboard everybody. Before we embark, I think we should give this beauty a name.
Cassie Munro: The big turd.
Carl Munro: The big rolling turd?
After that, Robin Williams did indeed keep calling it the turd or the big rolling turd.
I also found it most amusing to see all the things that would get sliced off the RV or come out from under it - the awning, the shopping cart, the boat ... The crew probably sat around laughing about what else they could get to come out of its rear end.