This is a silly example, but years ago I wanted to prove that you could write a non-trivial program in python using a single expression (because python's lambda only allows you to use expressions, not statements). And I managed to do that. And it's hideous. Any python programmer could theoretically understand what this is doing, but I doubt they would. Bonus points if you can guess what it does without running it!

    (lambda:
        not globals().__setitem__('sys', __import__('sys'))
        and not globals().__setitem__('this', sys.modules[globals()['__name__']])
        and not globals().__setitem__('time', __import__('time'))
        and
        #program
        [setattr(this, k, v) for k,v in {
                'set_color': (lambda c: w(['*', ' '][c])),
                'abs': (lambda t: (int(t) + (int(t) >> 31)) ^ (int(t) >> 31)),
                'w': lambda x: sys.stdout.write(x) == 0,
                'smash': (lambda t: -((t * -1) >> 31)),
                'color': (lambda n,k: set_color(smash (k & (n - k)))),
                'col': (lambda n, k: k <= n and not color(n,k) and col(n,k + 1)),
                'row': (lambda n: (
                                not w(' ' * (40-abs(int(n/2))))
                                and (col(abs(n), 0) or True)
                                and not w("\n")
                                and (abs(n) < 63 or n < 0)
                                and not time.sleep(0.05)
                                and row(n+1))),
                'triangle': lambda: row(-60)
            }.items() ] and triangle() )()