[CannonFodder52]

"Hmm, I need to overprice my hat. What to do?

• I have a generic soldier hat

The stash was to my knowledge pretty exclusive to the vietnam war. The specific Stash worn in TF2 is a reference to the Movie Full Metal Jacket. The Helmet band with a pack of cards and cigarettes is seen in Full Metal Jacket. In RL the stash was intended to hold foliage, bullets etc. People may have used it to hold cigarettes but the cards was probably Kubric taking a stab at the lack of seriousness of the soldiers ending other peoples lives.

It has a peace sign circling around it

One of the main themes in FMJ is the duality of man. This is brought up a lot during the movie. Thus the Stash directly taken from full metal jacket(A war hat) with a peace sign rotating around it pretty obviously represents this theme.
Oh and:

:O Full Metal Jacket's poster has a peace sign on the generic soldier hat on the poster.

:O He wears a barely-visible peace button on his chest

THEMED

PROFIT"

I dislike you...