It's fun, calorie-free, and won't get you pregnant
A good line to use wif a cute chick when ya wanna do something totally "innocent 'n' harmless" like rub her feet, give her a cuddly soothing massage, etc.
Telling a hot gal dat "It's fun, calorie-free, and won't get you pregnant" can also be effective for getting her to allow you total access to her warm softness wif your hands and lips, provided dat you are actually able to "keep it in your pants" (or at least just in her hand or mouth, if you're both naked). Good luck wif DAT, though --- once you get excited from savoring her exquisite flesh, her juicy-looking coochie may look awfully tempting for your painfully-engorged lulu! What you can do in dis case, though, is to either wear a condom or have her "relieve da pressure" manually/orally, and then you can safely thrust inside of her for at least a few minutes before your sperm-glands "recharge themselves" to da point where you would again be in danger of spurting helplessly while you're eagerly "soothing her baby-tunnel" wif your swollen "love-pipe".
It's easy, fun, free, legal, calorie-free, and won't get you pregnant
How you describe a proposed recreational activity to a girl to alleviate most of her "automatic" (i.e., uncertainties that would typically occur to her "right off the bat" whenever anything unfamiliar is suggested to her) concerns .
Telling a cutie that, "It's easy, fun, free, legal, calorie-free, and won't get you pregnant" when you wanna give her an "all over" massage is fine and dandy,. but how can you be so sure that this will all be true? I mean, just **you** try and "keep it in your pants" when you have a luscious-fleshed girl lying naked and submissive in front of you!