Runners use a lot of jargon that is not universal recognized. Here are some examples:
Splits - these are something different to a runner than, for example, to a gymnast or a cheerleader. Asking a gymnast to do negative splits would likely just confuse them.
LSD - isn't it obvious?
Fartlek - sounds a lot like "fart lick"... (hehe... Fartlek... )
Bonk - bonking to a runner means "hitting the wall" in more of a figurative sense - at least in the context of running.
Hit the wall - see previous.
Flats - to run in flats is a much better experience than to ride/drive on them.
Lactate Threshold - this has nothing to do with lactation.
RICE - is both a food and a way to treat injuries. Have you ever told a non-athlete friend that you were treating an injury with RICE, tell you they didn't realize that rice had such medicinal properties?
Stitch - for runner's this is not just what holds their clothing together.
Marathon - yes, even this term can be confusing, because some non-runners aren't aware that it refers to an event of a specific length (26.2 miles). I recently overheard one of my friends inform another, who asked, that a 10K race was a marathon!
Naked - runners usually work out with at least a stop watch, but many use a variety of other electronics, including gps's or other types of pedometers that estimate distance traveled, speed, and track actual running routes. A run during which you leave all these things behind can be referred to as a "naked" run. See the problem here? Yeah....
I'm sure this list isn't exhaustive. If you have any others you'd like to add, please leave a comment. I hope you don't get a side stitch and bonk and screw up your naked negative splits run, just because you decided to throw in some Fartleks!