Treats are luxury consumer goods/services. It's a silly, trivializing term in order to counter the elevated status that people ascribe to luxuries, and usually gets combined into phrases like "treat brain" (obsession with consuming luxuries) or "treat lad" (someone whose identity is wrapped up in consuming luxuries). People need to be reminded that luxuries are above and beyond what is actually needed and aren't worth the cost of ruin and human misery that entirely too many of them have.