In all ways but one it was your standard billboard, one based on Diet Mountain Dew's “Surprising Facts” TV campaign, in which we learn, among other things, that ferrets attack more people than grizzly bears and that the yo-yo was invented as a weapon.

In the billboard, we see a man and a comely woman in an office situation, with the words, “Attraction makes beards grow faster.”

That's the surprising fact.

But more surprising to Los Angeles motorists tooling past the Hollywood & Highland Center is that the man's beard appears to be growing.

And indeed it is. Every two weeks or so the agency that created the campaign, BBDO, attaches more hair to the man's beard.

“Because it’s in such a busy area, we wanted more than just a plain two-dimensional billboard,” says Peter Kain, creative director at BBDO's LA office.

“Part of creating the campaign was digging up surprising facts. The beard fact we had for a while, and this was the best opportunity to use it.”