Source : Free On-Line Dictionary of Computing

geek out
     
        To temporarily enter techno-nerd mode while in a non-hackish
        context, for example at parties held near computer equipment.
        Especially used when you need to do or say something highly
        technical and don't have time to explain: "Pardon me while I
        geek out for a moment."
     
        See {computer geek}, {propeller head}.
     
        [{Jargon File}]
     
        (1995-01-18)