Cliff Notes: It's OB without the
extra penalty stroke
and you rethrow from the original lie.
The complete explanation is defined in USDGC General Ground Rules #2 (pg 12 of 17 in the
Caddy Book):
2. Red stakes, red rope, or red flags denote the presence of a Buncr Hazard on holes 10, 13, 14, and 17.
a) Shots that come to rest in a Buncr Hazard must be rethrown. Rethrows must be taken from the original lie, prior to subsequent play by others in the group. If the marker has been moved, an approximate lie should be used.
b) Throws that land in the Buncr hazard count towards the player's score. But unlike OB, there is no extra penalty throw.
c) The lines bounding the Buncr Hazard are part of the hazard.
d) The Buncr Hazard rule applies even after the disc has come to rest on the island or green.
e) The player may not retrieve the originally thrown disc prior to the rethrow, except in the case of a putt from with 10 meters. Where a disc is retrieved in violation of this rule, a one-throw penalty shall be imposed without warning.
ERic