Soooo...ive just got a kit and included was the corn sugar for bottling....but I have some from previous batches....what would happen if I just threw it in the batch??
I depends on how much of it you use. It will boost ABV, but too much will give you cider flavors and thin your beer out.
The 5 0z or so will do almost nothing to a 5 gallon batch. "Too much" would be on the order of several pounds, I doubt that's what you're talking about.
"Anything worth doing, is worth doing slowly." ~~ Mae West