Asked of someone else it means do you feel like it, as in wanna lower it five centimetres or ten, or want to shoot the ball again. Said about yourself it announces what you have decided you want, as in the line I am going, Busan Joseon Beach. It is the blunt, close-friends version of 을래요. One line here uses a different fixed pattern built on the same shape, 안 찔래야 안 찔 수 없다, meaning there is no way not to gain weight however you try.
Register: casual, for friends and juniors; add 요 for polite