Some Halloween costumes, such as Dolly Parton or a man dressing up as a woman, simply call for large breasts. When your chest is not quite up to the job, you might need to create the illusion of bigger breasts. While you can often purchase fake breasts at a costume shop, making them yourself is pretty easy.
Place a deflated balloon inside your flesh-coloured knee high stocking. The stocking is going to cover the balloon so that it looks like your skin. Putting it in the stocking before blowing it up is much easier than pulling the stocking over the inflated balloon.
Blow up the balloon until it is the desired size. Tie the balloon. One balloon will be one breast.
Tie the end of the knee-high stocking into a knot so that the balloon stays inside it.
Repeat with the second balloon and knee-high stocking.
Put on a large bra or a tight-fitting shirt that will keep the balloons in place. Place the balloons inside the bra or shirt and adjust them so that they look the way you want them to.