I have had outdoor faucets leak before and manage to fix them, either by replacing the anti-siphon valve, replacing a washer, etc.
I have no idea on this one though.
We just moved into this house, so I am not sure the history on it, but the faucet in the garage leaks a little. The steps to create the leak is this:
1. Faucet with no connection and turned off - no leak
2. Hose connected with water off - no leak
3. Hose connected with water on - no leak
4. Turn off water while keeping hose connected - LEAKS
5. Disconnect hose - water gushes from faucet, then stops.
I am attaching a photo of the faucet, and where it's leaking from: