Levi Johnston has learned his lesson.

The teen father jokes he's going to use "protection" in a new ad for Wonderful Pistachios' "Get Crackin'" campaign. He fathered Tripp, 10 months, with ex fiancee Bristol Palin -- the daughter of former Republican vice presidential candidate Sarah Palin.

In the ad, the 19-year-old -- clad in a bright green Alaska T-shirt -- walks with publicist Tank Jones as cameras flash and paparazzi call out his name.

"Now Levi Johnston does it with protection," says an announcer as Johnston pops a nut in his mouth.

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The campaign marks Johnston's commercial acting debut.

Olympic swimmer Dara Torres, Sopranos' Vincent Pastore, Brady Bunch alum Christopher Knight and Jackass' Wee-Man will also appear in Wonderful Pistachios ads.