not anything... that is oversimplification. carbs are the one thing you can eat lots of after a heavy anaerobic workout (aerobic ones too, but not as much) due to the heightened insulin sensitivity, but even then, you can still get fat if you eat too many.
the trick is to take advantage of the post workout and eat a mix of carbs, whey protein, and some creatine (the protein and creatine are optional depending on your methodology). the carbs should also be high glycemic (glucose/dextrose is best for this purpose) as the effect is not long-lived (so macaroni may not make it in time to do much for you)....
basically there is no free lunch, the laws of thermodynamics cannot be broken, so no, you can't eat everything just because you worked out.... but if you work out, you can take advantage of the insulin sensitivity to shuttle glucose into your system, so KFC is out as are most solid foods (whey is acceptable because it's so digested, it actually behaves like sugar in your stomach)... though you could eat pizza after a workout and think you're not getting fat, the reason for this is your caloric deficit just delays the fat, but over the long-run, you will definitely get fatter (depending of course on your metabolic rate, which if its fast, you probably won't, but fast metabolisms have their own drawbacks).....
also, the glucose trick works better as you are more experienced in working out, so if you are a beginner, you won't benefit much, but if you have years of weight-training under your belt, you will have developed the experience to recruit so many muscle fibers that you will be in a better position to build an even greater insulin sensitivity and thus, better utilize even more glucose (thus the "pump")
Please Scroll Down to See Forums Below 
...be careful of fats, they'll slow down digestion. You wanna have all the nutrients absorbed before the insulin resistance kicks in.
