A person whose personal goals primarily concern material accumulation. Often accompanied by preppy (read: bland) sensabilities. A boring person with stuff.

Many engineers consider themselves to not be yuppies because they are obviously unlike those Biffs in marketing. (Engineer yuppies don't realize that (a) they have amassed stuff, and (b) after six years in the cube farm, they are now boring.)

I can't be a yuppie. I have weird hair.