This “Got Milk”-riff ad, the latest in the city’s efforts to get old people to put on condoms if they’re going to have sex, comes our way via WestSideRag, who sighted the sign at right on West 72nd Street near West End. “Age is not a condom” — no, no it isn’t. But even though you’d think over-50s would know that, having not been born yesterday, or even, say, 20 years before yesterday, people in the senior community are still going ahead and having sex without condoms. The dark side of this is the growing numbers of people who’ve contracted HIV at age 50 and older. The ironic side is that these are the same people who preached safe sex to us youngsters back in the old days. The sort of hilarious side is how parents will answer their young children’s queries about the nekkid lady in this prominently positioned ad. Practice what you preach, grams and pops! STDs are not cool.