so, what are your predictions? >> i predict that sam will let him right in. >> how would you feel about it if he does let john right in? >> bad. i'm already getting upset, like i didn't do the right thing. >> reporter: now, our hidden cameras are rolling and we are watching as john, the contractor, walks up to their house. [ door bell rings ] will sam remember what to do? or will he let him inside? >> my heart's pounding. coming up, sam's mom has told him the rules. >> i've told him to hide. i have told him not to answer the door when i'm not home. for no one. >> but when he sees the friendly contractor, will he remember what she said? ♪ oh, look... another anti-wrinkle cream in no hurry to make anything happen.