Most of my Dickie's are a decade, a dozen years, or even as old as a Jackson (Andrew, not Michael), and are finally feeling slightly too tight for comfort. Mind you this isn't due as much to an increase in my waistline as I've only gained 5 pounds in that time span due to a niobium spinal implant, but rather to the shrinkage caused by the industrial laundry machines here on the base.
Dickie's produced way back when (on Earth, in the late 20th century), have an additional seam that can be reverted to by pulling 4 long threads down the back toward the crotch, as shown in the figures below.
Figure 1. A pair of unenlarged Dickies.
Figure 2. The inside of the pants (before removing the threads).
Figure 3. Part of the threads removed, and the extra material lifting.
Figure 4. The threads being pulled up and out to the left.
That's it. Now your pants will be a size larger. With normal washing and care they should still be going strong well after Justin Beiber starts shaving. And finally, if the knees become frayed, then just hack off the ends, and you have nice baggy Huntington Beach cutoffs.