One of the most powerful and most respected family of programming languages by computer scientists. Lisp can rewrite itself on the fly, although this potential is rarely exploited. Mainstream Lisp dialects have steep learning curves, so they're rarely used outside of artificial intelligence, space missions, or computer algebra apps, but they are intended to be general purpose.
Dude 1: check it out, I just wrote a Google clone in Lisp while waiting for the bus.
Dude 2: damn, that's more parenthesis than the pennies in my granny's drawer.