Basically two people give each other their account info and sign in on each other's Xbox's. Once they're in they set that account has "HOME XBOX" and get the games off their account and download it, so when they sign back into their original account there will be the games they want there. BUT, you can never delete that profile off the xbox or allow someone else to gameshare because if that account is not the home profile then the games you were gameshared will not be playable.
Nathan-Angel pretty much summed it all up