A symbol of dominance or just a clever shot?
Hank Jennings’ domino originally contains the number six, seperated into two parts (three). Chris Mulkey explained at the 1999 Twin Peaks Festival that the number three represented “magic” and doubling it represented “mysticism.”
However, Josie Packard is often seen being intimidated by the domino therefore it could hold a deeper, more personal meaning. Another theory suggests it is the number of people Hank has killed.
Partway through season two, the number on the domino changes three times. This isn’t on purpose, it’s one of the few errors in Twin Peaks. The original domino was lost and replaced, hoping no one would notice!