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?

>>32

Whatever the source language, compilers that do type erasure are not to be trusted.

Think about it: just because the compiler thinks it "proved" that x location in memory is always going to be type y doesn't mean it actually will.