When it comes to frolicking in the surf, Britney Spears has made some real progress, at least if paparazzi pics are any indication. During a quiet weekend spent as a guest at Mel Gibson's Costa Rican estate, the custody-losing cautionary tale's wildest moment occurred when she indelicately picked her "Love Kills Slowly"-emblazoned bikini bottom out of her butt.

How do you say "unsafe at any speed" in Spanish?

Contrast that to a little less than a year ago, when she abruptly stopped her car in front of a Malibu, Calif., beach, stripped down to her bra and see-through undies and jumped into the ocean as an army of shutterbugs followed.

In between fidgeting with her puny swimsuit, Brit soaked up plenty of rays, zoomed around on an ATV, played on a boogie board and cooled off in the surf.

Photos: Brit in Costa Rica

She was joined on the low-key Central American getaway by her decision-making dad, Jamie, and her agent, Jason Trawick, whose presence and proximity to the attention magnet inevitably touched off whispers of a bubbling romance.

The rumor mill also began a-churning with bone-chilling pregnancy chatter, thanks to shots showing the lately gym-dwelling, athletically built Brit's slightly protruding belly (it's a look many of us in the real world sport after consuming more than, say, a single carb).

But Spears' camp vehemently denies that Sean Preston, 2, and Jayden James, 20 months, may soon add another member to their already step-sibling-filled family (oh, and daddy speculation has ranged from -- eesh -- ex-husband Kevin Federline to -- double-eesh -- her last boyfriend, mercifully off-the-radar paparazzo Adnan Ghalib).

Brit's itsy-bitsy bikini holds on for dear life.

"I want to make completely clear that Britney is not pregnant. There's not going to be a statement -- she's just not," a rep assures the London Sun.

Adds a "pal" of the bit of bulge, "It's a mix of water retention, unflattering clothes and people liking to analyze everything she does. Britney's getting herself together slowly but surely and isn't going to mess that up. She's far too busy to even be thinking about a baby right now."

One of the things keeping her occupied in recent days is her ratings-boosting, guest-starring stint on "How I Met Your Mother."

According to series lead Alyson Hannigan, Spears didn't exactly live up to her tabloid reputation, especially on her return engagement.

The actress tells USA Today that Britney was "lovely": "She's so sweet and polite. She's quite shy. We sort of bonded the last time and talked about dogs and clothes, girlie things. And now, when she came this time, I had my puppy, Oliver, with me, and she got to meet him. She bonded with Oliver, and he gave her kisses."

Hannigan also told the puppy-smooching story on "Live With Regis and Kelly" last Friday, which led guest host Jimmy Kimmel to joke, "I hope Britney doesn't end up pregnant!"

Next: Jess & Tony Cozy or Not at Ashlee's Nuptials?