Where they all try to think of nothing, but can't? I sometimes watch that bit and try to do it as well, usually lasting a whole lot less time than poor ol' Ray manages.
It's really hard to literally think of nothing, isn't it?
There are probably other bits in films that you've watched and thought 'not sure I could do that' I suspect? Like when Bond jumps onto that crane in 'Casino Royale'. There might not be though.
Best do some work...