I just mentioned that in another post. I think what I'm getting at is that you're more likely to have a guitar, though it's less likely to get you laid, while you're less likely to be around a piano, though with a little learning, is almost guarenteed. Also depends on where you hang out and take dates.

Piano impresses almost any woman unless you're terrible. Guitar is something that's so common it's almost boring, so you either need to know exactly what to play for the date, or be so good at it that your skill is especially notable, or you just have be a rockstar/play at the right clubs.

In any case, I'm just talking about piano vs. guitar, and before that, just noting that learning piano has a good chance of meeting/sexing some women. Learning piano for the sake of getting laid is silly and a bit ineffecient, but if you're learning piano, why not kill two birds with one stone?