Just go up to a cute girl in front of a windows machine, open your mac, and ask her "Which computer do you think is more sexy?" At the same time, place a cd in the slot loading drive, have loads of programs open, and use expose F11.
Make sure that pasty faced chav is next to you when you do it.
After that, kiss her. When she smiles, turn to the jerk and say "Can you do that on your Windows machine, batty boy?"
Of course, she'd have to be pretty geeky to be impressed by that