If your drink is at room temperature, ice will dilute it. To chill your coke quickly, spray it with an upside down can of compressed air.
Go Repairs Blog has a video with a few other ways to speed up chilling your drink, including the old tricks of wet paper towels and a salty ice water bath. But the upside down air can is the fastest of the methods.
It's fairly simple. Just take a plastic container, add a few sponges in it, and put your bottle in the centre of the sponges. Hold your air can upside down and spray between the bottle and the sponges.
The liquid chemical in the canned air absorbs heat from anything it comes in contact with, once it's out of the can. The sponge is to collect any water (which is a side effect of the rapid cooling) -- you can replace it with cloth if you don't have sponges to hand.
A few precautions: Avoid using glass in the container or a glass bottle as the rapid freezing can cause it to crack or shatter. You shouldn't do this in a room with no fresh air, and use gloves while handling it. Also, canned air can add a bitter aftertaste, so wipe your bottle clean before you open it.
4 Quick Tips for Keeping Your Drinks Cold [Go Repairs' Blog]