San Francisco Detour

A sexual act in which a male places his penis head against either nostril of his partner just prior to ejaculation. Once ejaculation is imminent, the male exhorts, "I'm going to cum!". The 'detouree' then takes a deep breath through the nostrils, forcing the seminal fluid into the stomach by way of the nose--rather than the mouth--as is typically expected.

Note: If two men ejaculate in either nostril of the 'detouree', this is referred to simply as: A double detour.