Any type of sexual activity that leads to orgasm including masturbation, anal sex, oral sex and intercourse can trigger sex headaches.

CNN: Sex headaches

"There's been some speculation about whether teenagers were substituting oral or anal sex for vaginal sex and I found that wasn't so, " says Rosenbaum.

CNN: Virginity pledges don't mean much, study says

In a recent survey in Cambodia, 40% of men who had had anal sex with other men in the previous month had also had sex with women in that time.

ECONOMIST: The struggle against AIDS in Asia is far from over

Former Penn State assistant football coach Mike McQueary also testified Tuesday, describing what he thought appeared to be Sandusky having anal sex with a boy in a shower inside the university athletic facilities.

CNN: Alleged Sandusky victim details abuse

According to grand jury documents, a graduate assistant told then-Penn State head football coach Joe Paterno in 2002 that he had seen Sandusky performing anal sex on a young boy in a football complex shower.

CNN: STORY HIGHLIGHTS

"Anal examinations conducted to "prove" same-sex conduct are scientifically invalid and, furthermore, if they were conducted without the men's consent, contravene the absolute prohibition of torture and other cruel, inhuman and degrading treatment or punishment under international law, " said Mr Mawanza.

BBC: Zambian men charged over gay sex