Perhaps you've heard of "cow tipping" - the legendary prank of sneaking up on a dozing cow and pushing her over.

Yes, it sounds mighty cruel, but the good news is it may very well be nothing more than an urban legend.

According to researchers at the University of British Columbia, the prank is practically impossible to do.

By calculating the level of force required to topple an average cow; estimating the angles between left hooves, right hooves and the point of push; and the resistance of the cow to the downward pressure, researchers determined that two people could exert the required force only if the cow made no reaction at all to the initial touch.

They say more than likely, a successful tipping would require at least five people.

And even then, it may be "possible" but not very "probable."