In League of legends, Killing minions or enemy champs grants gold and is your best source of Income. Like the immigrant saying "a dollar and dream" set backs and new opportunities can grant you amazing things. In league of legends, to perform the 1 CS and a dream, you have either have 1 cs by 4 min and pop off by the end of the game, and achieve the dream of winning or to simply have an early gank set you back, only to pop off an carry in that game.
Voyboy: "Tyler don't worry, I pull of the 1 CS and a dream this game"
Tyler1: "Voy, you have 1 cs on Ryze at 4 minutes. Unless you somehow pop off, I don't know if we win"
20 Min later: Tyler: "AND VOYBOY WITH THE PENTA, WTF HE REALLY PULLED OFF THE 1 CS AND A DREAM"