— -- Airing Friday, October 2, 10 pm ET on ABC

“Shark Tank’s” Mr. Wonderful, Kevin O’Leary, brings his expertise as master of the art of the sell to “20/20’s” second on-air sales challenge. For this challenge “20/20” has recruited college seniors with little to no sales experience to compete for a coveted spot in a sales boot camp with O’Leary. He shares his tricks of the trade with the six semifinalists before throwing them into the shark infested waters to see if they will sink or swim. “20/20” heads to New York City’s Union Square Park to see which of the final three contestants learned the most in a competitive, hidden camera sales experiment. The students will sell cupcakes out of a truck from a company O’Leary invested in on ABC’s “Shark Tank,” Wicked Good Cupcakes. O’Leary and ABC/ESPN anchor Hannah Storm provide live direction and commentary and award the 2015 winner with a special prize. Secrets of the Sell airs on “20/20,” FRIDAY, OCTOBER 2 (10:00-11:00 p.m., ET) on ABC. Link:

And: Have you ever wondered what it takes to drive one of those iconic Mary Kay Pink Cadillacs? “20/20” reports on how beauty consultants for cosmetics giant Mary Kay rise to the top, in this direct selling business, where products are not sold in stores or online, but person to person. “20/20” speaks to current and former Mary Kay beauty consultants about how to master this sell game, the benefits, the challenges and everything else in between about running a Mary Kay business. Rebecca Jarvis reports.

Also: Holiday season shopping brings one sure thing: advertising and lots of it. Companies are competing harder than ever, promoting mega sales, miracle products and making big promises about their products. Many seem like great deals too good to pass up, but could they be just too good to be true? Rebecca Jarvis reports.

“20/20” is anchored by Elizabeth Vargas and David Muir. David Sloan is senior executive producer.