(slang) a variation of the
phrase lead-
pipe cinch, a doubly sure or doubly easy thing.
Lead pipe refers to a midwestern and western US
form of galvanized
iron pipe (which looks as if it were
lead). For saddling and cinching (fixing a saddle securely) the sort of horse that expands its belly, a
short length of this so-called
lead pipe was slipped under the saddle strap and turned like a tourniquet, the
work assisted by a few knee jabs in the belly. Thus the horse was forced to deflate and the saddle was cinched tight, that horse now being double (
lead-
pipe) cinched.