Matt: My girlfriend and I have seen these sun billboards around town lately that say, “Use your cabeza.” We both have our guesses about what they're advertising, so we ended up making a bet. If I win, she has to walk around for a day wearing a convincing, fake beard; if she wins, I have to wear a tutu for a day. She thinks it's an ad for a new suntan lotion, but I think it's an ad for a cruise line. — Paul Savage, Hillerest

Dear Matt: My boyfriend and I made a bet about a billboard. He always thinks he’s right, in a kind of funny, boyish way. Two conditions: The loser has to do it on the weekend, and the loser can’t stay home all day but has to go out and run errands. I’d laugh for a week if he had to wear a tutu! — Kristin Schritter, San Diego

Hey, Matt: What’s the story with all these billboards with the sun peeking out from the bottom? I’ve also seen a pile of postcards with the same sun on them in a couple of bars. Is it some kind of environmental! global warming thing or a tourism thing? What’s up? — Jamie Robbins, San Diego

All three queries arrived in the same mail. Coincidence? Or does that little minx Kristin get around more than Paul knows? I don’t know how many environmentalists spend their off hours writing postcards in bars, but at least Jamie’s guess is imaginative. Fueled by a bit o’ cerveza, maybe. Which leads me directly to the answer. I’ll supply it only if Kristin and Paul promise to run errands for one day dressed in beard and tutu, because they’re both way off base.

About five minutes into our research on this, we learned the billboard company is sworn to secrecy. When they saw us coming up the walk with a big peach pie and some chocolate milk, our favorite social lubricants, they slammed the doors and pulled the shades. We could hear them whispering, so we knew they were in there. But all we got was a note balled up and tossed through a transom that said something about all of Western civilization disintegrating if they told us what was going on. I don’t recall any reference to global warming, but maybe that figures into the end-times scenario too, So...we have a secret billboard. The ultimate noncommunication? So much for the logical approach.

As luck would have it, the elves took off for a Baja weekend to recover from our rebuff and came back with at least part of the answer. The sun on the board is the same one you’ll find on the label on Sol beer, a 100-year-old Mexican brew. You can see jt advertised locally on Mexican TV stations, mostly during soccer matches. If you’ve seen it in TJ bars, it’s the one sold in a clear glass bottle with a slice of lime in the neck.