To enable the admin menu You'll have to press [Ctrl]+[Alt]+[V] and it's typically only useable by Lindens, and SIM owners. However enabling this allows you to locate anyone on the map, and send teleport requests to people who are not on your friends list.
Open Debug Menu
To open debug options You'll have to press [Ctrl]+[Alt]+[D] while in-game. Here you can control various things such as turning on wireframe mode, or making invisible objects visible. Note any change you make will have no effect on other players. To disable debug, press [Ctrl]+[Alt]+[D] again.