lambda lambda lambda

Hey /prog/, I found this last night:

(define (foo) (lambda (g) (((lambda (f) (g (lambda (arg) ((f f) arg))))) (lambda (f) (g (lambda (arg) ((f f) arg)))))))

What does it do and how do I use it?

>>24
Lisp would be "GRUNNUR" because it is at the end of the programming language food chain.