A Twinkie is a a Hostess Brand Snack Cake, noted for it's blond color and creamy filling. The name is often applied to young men who are blond and have a creamy filling (although you generally have to work harder to get it out :-)
Twink is an umbrella term applied within the gay community in terms derisively and blankly to stereotype/describe young, attractive guys. Though among the common GayStereotypes, GayTwinks are not necessarily one huge clusterfuck.
Anyway, I think its kind of coincidental that twinks buy whatever they're told to, and the twink stereotype of youth, beauty and overspending is the only thing we ever get to see on TV. You know, television, the media brought to us almost for free thanks to advertising dollars by big labels? Hmmmmmmmm.... I smell a ConspiracyTheory?.
Yeah, in QueerAsFolk, a show notorious for using such stereotypes, folks are constantly buying each other's love. Emmet is going out with George because he gave him a rolex, Tedd gave him a rotating bed and a neon sign to keep him happy, Justin gives Brian sex in exchange for tuition, etc. The fact that Brian is an asshole is irrelevant once he gives them a nice make-up present like free marketing, or lets them ride/drive his jeep home.
You may want to check out the description of GayCommunity.