'Mae West' is a name given to a type of malfunction in the deployment of a parachute. When a Mae West occurs, one or more of the shroud lines ends up stretched over the top of the canopy after the 'chute opens, pulling down on it so that the canopy forms two large bulges instead of the usual hemisperical shape of the old WWII style parachutes. More officially, and with greatly less humor and imagery, this malfunction is called a 'line over'.
Training instructors enjoy describing this to the class in ground school. It can be a serious problem, though. The distorted canopy does not do its job well, and a hard landing will surely result. The 'chute may also be difficult or impossible to control. The most life-threatening possiblility is that the nylon line rubbing against the nylon canopy material may generate enough friction heat to cut through the thin canopy, defeating it altogether and sending the 'chutist plunging in an unintended free fall.
The standard way to deal with a Mae West, as our instructor taught us, is to haul in the shroud lines on one side to spill the air out of one of the bulges, hopefully restoring normal operation. If that fails, continue so that the canopy collapses completely allowing you to deploy the emergency parachute. Yeah, right. As he spoke, I tried to imagine myself calmly doing this, but concluded that, for me at least, Mae West = death. "But don't worry too much about this--it never happens," we were assured by the instructor.
Well, as ironic fate would have it, that same instructor experienced a classic Mae West on the first demo jump performed in the field for our benefit and encouragement just before our own first jump ever. We were watching from the ground, having interrupted practicing our PLFs (parachute landing fall). "Look, something's wrong. Fuckin' A! It's a Mae West!" "No shit! Can't be!" "Did they do this on purpose?!"
We students focused intently on the descending instructor, waiting to see the standard procedure played out for us in this rare opportunity. The other ground instructors were silent, following the jumper with concern through binoculars.
But, no, it didn't happen. The instructor just rode it out. He landed in trees about five miles away from the landing zone. It took the rest of the day just to find him.
That was our first practical lesson in parachuting.