don't ask them at all. Just get some booze and do it without them knowing.If you do ask them, and If they are responsible parents at all, they will say no, and possibly punish you for it, and question how many other times you have gotten drunk or what other drugs you have done. You will be setting yourself up for a butt load of trouble. Stick with the sneakiness, if you get caught, yes you'll get in trouble bu tat least you may get a drink before hand. IF you ask first, you probably won't get squat!