Assuming you are speaking of table sugar, yes it will increase your ABV; but in the process it tends to "dry" out your beer, reducing the flavor you get from the malt, and adding sharpness that you may not want. If all you're after is a beer that will eff you up faster, then by all means go ahead; but sacrificing flavor over ABV , and getting possible "fusel" (literally, 'hot' alcohol flavor) in your finished beer is technically a fault. And it will also give you REALLY nasty hangovers.