/vä-diŋ/
[from VAD, a permutation of ADV (i.e., ADVENT), used to avoid a particular admin's continual search-and-destroy sweeps for the game]
n. A leisure-time activity of certain hackers involving the covert exploration of the 'secret' parts of large buildings -- basements, roofs, freight elevators, maintenance crawlways, steam tunnels, and the like. A few go so far as to learn locksmithing in order to synthesize vadding keys. The verb is 'to vad' (compare phreaking).