When someone (probably someone low class) takes a loaf of bread or cake and has sex with it until he eventually busts a nut, causing it to fill up with semen. This makes it like a twinkie because it's bread with cream.
"That fly gansta, Fitty Cent just went and busted a nut in some pound cake, making it a Gansta Twinkie"
by UberCream May 6, 2007