More than likely not. I don't think one can of Coke would be enough to do any real serious damage. You may, at worst, have to pull the heads and clean the crap off the valves, tops of the pistons and intake runners. I would start by pulling the intake manifold and look down the intake ports at the valves to see how much sticky stuff has built up. Maybe even roll the engine over until the intake is closed and squirt some sort of cleaner down and soak it out with a rag until you get it clean then put it all back together, change the plugs and then go beat the crap out of the guy who did this dasturdly deed. I would fire it up and let it idle for about 15 minutes then SLOWLY (SLOWLY) pour a glass full of water down the carb. You'll have to keep the RPM's up as you do this. The water will help clean anything that might have stuck in the compression rings on the pistons. Then go beat the crap out of this dude.
Oh yea, after you've got it back running good change the oil and filter. The go beat the crap out ......... ;-)
Good luck. Hope you don't have to do too much else and it turns out OK.