Warning: This does not apply to one night stands. We repeat, do not say this to a man you just met. Many of us have endeavoured to spice up our sex lives with dirty talk, as per the advice of countless sex therapists. However, unless we've had a few for dutch courage, things can get awkward pretty quickly. (What IS the best sexy word for penis?!) So we were pretty relieved to find out that simply saying "I love you" during sex is the key to a more satisfactory experience for everyone. (See what we mean about the one night stand?) Scientists from Chapman University in the US analyzed the answers of 39,000 married or cohabitating heterosexual men and women who had been with their partner for at least three years. Three quarters of all respondents (male and female) that say "I love you" during sex reported satisfactory sex lives Other key ingredients for fulfilling sex lives were praise for what your partner did right, and the ability to laugh at something funny that happened during love-making. (NOT with the girls - with your partner you scallywag.)