YSK: Most recent cars have a keyfob button combination that will let you roll up or down the windows

Why YSK: If you leave your windows in the wrong state by accident, you don't need to get back into your car. If you've got out of your car and forgotten to close your windows, you can close them while you lock the car. If your car is hot, you can open your windows and let it cool a little without having to get inside. If you absent-mindedly close your windows on a hot day and leave a pet unattended inside, you can roll down your windows much quicker than having to rush over to your car and fumble with the buttons.

To do this: On some cars, you press-and-hold the lock/unlock button. On others, you press the lock/unlock button twice, or press then press-and-hold. Check your car's manual or google it on whichever your favourite search engine is.