Sorry fellas, I didn't mean to hit you so quickly with yet another Style Lexicon (as they say, "Variety is the spice of life"), but all this madras/preppy talk somehow pointed me to this humorous definition on Urban Dictionary. I thought it was worth sharing, so here it is:
Really a chimera of two existing groups, the prepster is someone most likely raised in the suburbs and very preppy, that moves to a very hipster centered city (Brooklyn, Portland, Austin), and due to scene exposure adopts certain hipster trends whilst retaining the preppy spirit. Specific examples are skinny jeans with boat shoes, or skinny Nantucket red jeans, cardigans, and keds (although arguably of preppy origin, now adopted by the hipster). The prepster has the ability to flow seamlessly between the two scenes, adopting the traditional seersucker and polos while home, and looking very trendy at loft parties in Williamsburg. This emerging scene has been officially typified by Brooks Brothers new Black Fleece line, designed by Thom Browne, and the new J. Crew Men's store being created with help from Jack Spade. The major difference between the prepster and hipster is money and cleanliness. Drug use also shifts from pot to coke.
Taylor: Hey, have you seen my seersucker shorts, I need to go sailing tomorrow with the rents.
Thom: Yeah, they're right next to your skinny jeans from Uniqlo and your really dirty tee shirt.
Taylor: Dope, thanks.
Thom: Dude, you're such a prepster.