
My kids have been doing that for a log time now with iPhones. You can change the log in name on a phone or pad ... So temporarily log in as someone else, download, then reset to your original name. Won't allow update and all that, but works for quick pirating.
It's easier though to simply set up a home network and have all purchases move between your machhines. You're allowed up to 5 machines on a home net, so TomTom actually cost me only $20/each for everyone in the house.
PinkHat and I have reciprocal "Snag every new purchase" from each others itunes, so she buys a game, i get it. I buy some tunes, she gets them.
I was quite pleased when Apple put this together because I didn't like my kids thinking they were doing something wrong by grabbing each others apps.