Run `a = []` - and you should get 200 OK.
Run `a << a` - and you get a 500 internal server error.
Normally the sandbox will handle a problem by some kind of exception or text warning (e.g. on timeout), but it can't even handle the request.. so have I broken it?
Inspired by this video from a guy who works on the sandbox: http://www.youtube.com/watch?v=6XxCOYco3Eg