After asking nearly 2,000 people why they'd had sex, the researchers have assembled and categorized a total of 237 reasons.
[snip]
The researchers, Cindy M. Meston and David M. Buss, believe their list, published in the August issue of Archives of Sexual Behavior, is the most thorough taxonomy of sexual motivation ever compiled. This seems entirely plausible.
[snip]
some respondents of both sexes explained that they'd had sex "to get rid of a headache." It's No. 173 on the list.
Link.
