A lot of the research that goes on in the scientific community is totally pointless (not the stuff about saving lives or the world or whatever) but this particular nugget of information is one that we could definitely use.
Everyone knows that there are plenty of positions in which you can do the deed, and that some are perceived as sexier or better than others. Some, indeed, come with an inherent risk of pure, unadulterated danger that only enhances the frisson of it all, and should be avoided if you want to keep your bits intact.
Thankfully, scientists in Brazil have been working hard (no pun intended) on finding out what the most dangerous position of them all is, and therefore increasing the temptation to try it out, what with the aforementioned danger and all.
It turns out that the 'cowgirl' has been deemed the worst offender when it comes to injuries, accounting for more than half of all fractures of the penis, which we can only imagine is more painful than it sounds. The 'cowgirl' position involves the woman straddling the man, to use the terminology of the researchers that looked at men and women as opposed to other common combinations.
To add to the gruesomeness of the whole thing, the men who fracture their members this way also hear an audible snap when it happens, in case the incredible pain doesn't tip you off first.
Runner up in the sexy/danger category was 'doggy style' (the woman on all fours), which accounts for 29% of penile fractures while on the other end of the spectrum, dependable old 'missionary' was deemed to be the safest. It'll never let you down.
The disclaimer, as pointed out by Animal New York, is that the study appears in the journal entitled Advances in Urology, so the focus will be on penile injuries, rather than general injuries caused by one position over another. Still, everyone just stay safe out there.