Woah, alright.. Woo... Okay. Buttsex. Man..
According to a survey by the CDC in 2005, <a href=http://www.cdc.gov/nchs/data/ad/ad362.pdf rel="nofollow">"The survey showed that 40% of men and 35% of women between 25 and 44 had engaged in heterosexual anal sex; in 1992 a similar survey found that only 26% of men 18 to 59 and 20% of women 18 to 59 had."</a>
Thanks to Wikipedia, We can all know about the great danger of anal. While it is an Indeed exotic act, It can cause serious damage(especially in men). And for women, the main danger here is pressure on organs.(And anal fissures.) However, for men, (and this is just a wild guess, really) the danger is in prostate damage.
"Okay, so Just HOW did your prostate rupture?"
"Uhh.... I fell."
"Onto a bowling ball?"
"Umm... well.. 2 bowling balls and a pi-"
"Get the hell out of my office."
"But I'm bleeding anally!"
"Shove A band-aid up your ass, then!"