Who's the Barest of them All?

Andy Baldwin -- the consistently half-naked famewhore from "The Bacholor" -- has challenged the other shirtless wonder, Matthew McConaughey, to a tops-off rematch of the Malibu Triathlon.

Even though Baldwin smeared Matty during the race at the 'Bu, he still wants to go another round -- this time in Andy's home turf of DC. And it's totally not to draw attention to himself ...