WordNet (r) 3.0 (2006):

gopher hole
    n 1: a hole in the ground made by gophers

The Jargon File (version 4.4.7, 29 Dec 2003):

gopher hole
 n.

    1. Any access to a gopher.

    2. [Amateur Packet Radio] The terrestrial analog of a wormhole (sense 2),
    from which this term was coined. A gopher hole links two amateur packet
    relays through some non-ham radio medium.