mahogany reef
n.— «Old-time sailors with hangovers explained away their misery by saying they had been caught in a rum front, and hung up on a mahogany reef (a bar).» —“It’s no fish story: Yacht sales brisk in landlocked Yuma” by Dick Gillespie Denver Post (Colo.) Jan. 19, 1994. (source: Double-Tongued Dictionary)