Before a few, weeks Facebook rolled out a new feature called “Places”.
It lets you and your friends check in to locations. If you'd like to keep your location private, follow these steps:
1. Log in to Facebook.
2. From your Account menu, choose Privacy Settings.
3. Click the Customize option (if it isn't already selected)
4. Click the "Customize settings" link.
5. Under the "Things I Share" heading, all the way at the bottom of this section, there are two things you may want to change:
By default "Places I check in" should be set to only be visible by your friends.
Use the drop down menu to change it.
6. Below that option is "Include me in 'People Here Now' after I check in."
This will let people know you're at a particular location via the location's page or in a search for people near you.
It’s enabled by default. Uncheck "Enable" if you don't want this.
7. The last and important thing: If you don't want your friends to check you into Places, sharing your current location with a people you maybe do not know; go down to the section called "Things Others Share" and find "Friends can check me in to Places."
Set this to "Disabled" if you don't want your friends checking you in.
Keep in mind that any friend could potentially check you in anywhere. You don't actually have to be there. If you don't want anyone to do so, turn it off.