One thing that I have found about Japanese men in particular (not so much other Asians, at least not to the same degree) is dropping little comments about how big cocks are not so great, "It hurts if it's too big, doesn't it?," etc. Japanese people love this sort of "little white lie," and making any comment about penis size (but especially one that appears to deprecate large penises) is a hint that the guy is hung like a horse. This also applies to complimentary comments about another man's (e.g. your) penis; Japanese guys who have commented on my bulge, said things like "Oh, I'm jealous, you must have such a big American cock," and so forth have invariably been humongous.
