This is a design of mine for stickers, T-shirts etc. You can replace Levente's picture in the middle with your own babe's if you wish. The size should fit newborn onesies, but you can enlarge it for adult T-shirts as well. You can have it printed on the chosen garment (or at some places even on cups) at copy/print shops. In computer shops you can buy special printer paper that can be ironed on the T-shirt at home. This works, too, but in this case you have to mirror the original picture with a photo editor program before printing it out.
This is how it looks "live" (Hungarian text version):
©Nandu Graphics (me), but it's free for everyone!