Don't eat anything with sugar in it for 7 days. I'm talking donuts, cookies, sodas, fruits, fruit juice, etc. Things like rice and potatoes are okay cause there's no sugar in them. On day 7, stop wearing deodorant. You should notice your armpits don't smell. If you want to have more fun with this, go an extra couple days of not eating the sugar, and still not wearing deodorant. Then eat something with sugar in it. Within a couple hours, you should notice your armpits start to smell again.