We're here to talk about the best threesome sex positions-and we'll get there, we promise! But before you jump into bed with a third person, there are a few important threesome tips to keep in mind. Ninety-five percent of men and 87% of women said they had fantasized about sex with multiple partners. When Men's Health advisory board member Justin Lehmiller, Ph.D., host of the Sex and Psychology Podcast, author of Tell Me What You Want, surveyed over 4,000 people on their sexual fantasies, he found that having a threesome is the most common sexual fantasy among Americans. At some point in your life, you’ve likely fantasized about having a threesome.