Objective C

Objective-C implements weak typing, blocks (aka anonymous functions or closures), key-value coding (aka accessing an object's methods and properties as if the object was a dictionary), monkeypatching, etc. It's a dynamic language with the power of C. It's Ruby and Python's uglier but more efficient sister. It has its own quirks that might put you off at the start, but the more I learn about it, the more I like it.