Which language would annoy a PHP user?

We have nobody who coordinates the programmers at the company. Everybody uses the technology he wants.

Which programming language would you suggest to learn that would annoy a PHP user (who knows a bit of Java) and give him a bad time if he has to take over a project?

>>34
That mostly seems to be a problem of memory manipulating, unchecked languages like C, are you sure that's really a problem of Haskell?
I mean, that is pretty much the point of Haskell that everything is proved mathematically before compilation, except, maybe in monads.
But I guess, the dangerous monad stuff is hidden in the framework, so if the framework guys fuck up, that's another problem.

See, I'm not claiming that Haskell is perfect (in fact, my ghc version has a proven compiler bug which renders yesod unusable), but after all, the typing seemed pretty much thought through.