A ~16-18ish kid tried this on a recent SYD-LAX flight. I was in 1A and he sat down in 2A. The FA came by about 10 mins before takeoff and asked to see his BP. He showed her the BP with 2A on it.. she looked confused, and turned back to the galley. As she's turning around she notices that the BP with 2A on it is for his LAX-SAN flight, not SYD-LAX.
He then "found" his other BP -- 53K. Gotta hand it to him. Bypassed C completely, went right for three class F suite.