Remember the old gag about "Save water! Shower with a friend!"?

For better or worse, it's back. I recently happened on a variation on the joke in a green public service announcement (PSA) by Ogilvy Advertising London for MTV Networks International. The one-minute spot shows people urinating in public places to a sacred-music sound track. A guy with a suspiciously official-looking cap waters a fountain; a female squats in front of a cathedral; an intrepid fellow, presumably endowed with the risk-taking gene, does his thing while bouncing on a trampoline. The montage closes with an exhortation: "Save water. Flush less." Ha.

The spot is one of ten promotional clips and short films that the company recently began distributing as part of MTV Switch, a year-old initiative intended to encourage its youthful audience to make planet-friendly lifestyle changes. Other recent PSAs warn viewers of the dangers of greenwashing and encourage them to get away from their video games and PCs and spend more time out in the real world. The ads all reflect MTV's trademark tongue-in-cheek style and aim, according to John Jackson, the company's director of social responsibility, to prompt action through entertainment, not fear.

The PSAs will be available across MTV's global network of 165 TV channels in 162 countries. It's a worthy and, yes, entertaining initiative, in an adolescent kind of way.

Speaking of which, the, um, urination ad is called, for reasons that escape me, "Slash." I don't get it. Why not, "Imagine World Pee's?"