When you add Contacts, whether in-game or a Game Center/Facebook friend, you have the option to gift them clothing and accessories for their wardrobe. Gifting costs cash and stars. Some gift prices vary from your own Kustomization wardrobes.
To gift someone, open up your contacts list and find someone you want to gift something to.
If you are dating an in-game character, you will be able to unlock gifts for them based on your relationship status. Buying clothes for your date can also improve your relationship points. Note that if you are dating Dirk Diamonds or Willow Pape, you cannot gift with them.