Intercrural sex, which is also known as coitus interfemoris, thigh sex, thighing, thighjob and interfemoral sex, is a type of non-penetrative sex in which the penis is placed between the receiving partner's thighs and friction is generated via thrusting. It was a common practice in ancient Greek society prior to the early centuries AD, and was frequently discussed by writers and portrayed in artwork such as vases. It later became subject to sodomy laws and became increasingly seen as contemptible. In the 17th century, intercrural sex was featured in several works of literature and it took cultural prominence, being seen as a part of male-on-male sexual habits following the trial and execution of Mervyn Tuchet, 2nd Earl of Castlehaven, in 1631.
In modern times, intercrural sex is commonly practiced in relationships of various orientations; adult women are said to use it to stimulate orgasm and in Paris, it was commonly performed as a part of prostitution. In parts of Africa and Asia, the practice is normalised and is carried out among heterosexual and homosexual males. In South Africa, it was used to combat acquired immunodeficiency syndrome (AIDS); this practice was eventually phased out.
Knowledge of intercrural sex that was extracted from studies and its relationship to AIDS and pregnancy is low. It has been reported as a means of safe sex for human immunodeficiency virus (HIV) positive patients and has a lower risk of infection than peno-vaginal sex. Studies have found a fluctuating percentage of sexual assault cases have involved intercrural rape, with little to no physical evidence.