Pony, in this instance, is another word for Trojans. The saying "pocket full of pony" refers to a pocket full of condoms. In order to sound as relevant and up-to-date as possible, you mustn't make pony plural when using this phrase. This phrase was slightly originated by Prince, but made popular by music artist Deno Benz in his duly titled song "Pocket Full of Pony".
"Sup bruddah? Whatchu gettin' into tonight my dude?"

"Wassup my brotha? I'm lookin' to bust a nut tonight. I took a shower today for the first in a week and I got a pocket full of pony. Lez get sum bitchesss! Wooooooo!!"

"Pocket full of pony. Piss drunk, super lonely. Spongebob macaroni. Where the fuck's my pony?" -- Deno Benz
by CrystalGuyzer February 4, 2012
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