There was a lot of hidden code found in Jelly Bean referencing different user accounts. The code wasn’t finished or at all usable to a normal user, all being invisible. Although, with a quick hack, it is actually usable! Now, this procedure requires root, and may be dangerous. None of us are responsible for any possible damages or data loss, so do this at your own risk. Make sure to do a backup before attempting this. Also make sure you’re on a Jelly Bean ROM (duh).
You should install Terminal Emulator from the Play Store first (get it here). Then type:
pm create-user test
You can of course switch “test” for whatever you want to name your second account. The accounts can be switched by holding the power button. The second account is limited in many ways, but not limited in a few others. The settings menu is less populated but the second account can still see text messages. Here is a note from the dev who described this method:
At the moment, this isn’t extremely usable, ie texts from the primary user’s still show in the 2nd test account. But, with the right launcher installed, and hiding the apps from the drawer on the 2nd account, this can still be usable in its current form.
1.) Label the 2nd user Guest
2.) Use Nova or Apex as the launcher for the Guest user, and hide all of the apps you want(texts, social media, email, etc) from the app drawer.
3.) Setup a security lockscreen on the primary user to prevent Guests from gaining access(each user has different lockscreen settings)