The idea of this drink is that it's really cheap and will get you and your broke-ass friend really drunk for next to nothing. The key is the type of whiskey and cola you use.
I prefer to buy a handle of Ten High and a 24-can case of President's Choice cola. This is enough alcohol and mixer to get like 6 people drunk. The best part is that because it's all crap, it only costs about $15(USD).
So yeah, grab a big-ass plastic cup. Make sure it's not clean. Residual liquid from the last drink had in it is even better. Toss in a few ice cubes, pour in a bunch of whiskey, and the top off with a can of cola.
Drink up, you jobless fuck!