Super Dew is the resultant when a aficionado (read - warped person whose quest is to find the ambrosia of caffeinated beverages) changes the ratio of syrup to soda water when procuring a cup of tasty Mountain Dew.
The process involves taking apart the dispenser head and just dispersing the delicious syrup into the cup, then restoring the soda fountain to its original state and filling the remainder of the cup with normal Mountain Dew. For those who enjoy oral masochism you can attempt to drink the pure syrup.