How much does an NFL hit really hurt?
Kevin Christ, Hamilton, NY

A crapload. Why? Because tackling is basically akin to attempted murder. “When you’re chasing a guy, you’re running tall,” explains Houston Texans Linebacker DeMeco Ryans. “But as you get closer, you have to sink down in your hips and explode, striking up and through him until his back is on the ground.” sounds pleasant.

But a monster tackle is not only physically painful—it’s humiliating too! “I’m trying to knock him out, so he knows he was dominated,” Ryans says. “We call those ‘woo hits’ in the NFL, because as soon as one happens you hear the crowd go, ‘Wooooo!’” And if a guy bounces back up? “You know You'll knock him out again. And right before you do, you know he’s thinking: 'Oh, my goodness, please don’t kill me.'"

Could you actually die as the result of a nasty hit? Nearly, according to the Doc we consulted (see above). The bottom line: Thank Jesus you’re a desk jockey and not a running back.

Can airplane travel really cause brain damage?
Todd Spadeson, Denver, Colorado

Yes, but you, Captain Colorado, might be spared. “Those who aren’t acclimated to higher altitudes may have a hard time breathing during flight,” explains R. Douglas Fields, Ph.D., of the National Institutes of Health. "And lack of oxygen can seriously damage neurons.” If you’re traveling through time zones, beware: A study of flight attendants found they had high concentrations of stress hormones, which can cause permanent shrinking of brain cells and loss of memory. And that can lead to…Sorry, what was the question again?

What is the most difficult surgery?
Greg Tyson, Wichita, KA

In surgery as in sex: twins! “No two separation procedures are the same. Every situation is unique and must be planned with painstaking detail,” says Steven Y. Park, M.D., of New York Medical College about the world’s toughest procedure—separating conjoined twins. “There are pediatric neurosurgeons, pediatric surgeons, plastic surgeons, and vascular surgeons present.” Even with all those pros, twins connected at the heart have never been successfully separated. Except for the Olsens.

Why are tongue twisters so hard to say?
Kirk DeVault, Jacksonville, FL

Don’t believe Cosmo—even the clumsiest of tongues has laserlike precision. So why is it so damn hard to say, “She sells seashells by the seashore” five times fast? When researchers at the University of Illinois asked college students to read tongue twisters alongside everyday sentences, they found that in addition to being difficult to say, these dastardly phrases take longer to write on paper. What does this mean? That we trip over tongue twisters because they trigger a cognitive failure, not a physical failure. And now that your tongue is off the hook, it can get back to failing at foreplay.