A key ingredient required for the carrying out of proper pwnage. One acquires pwnsauce by developing legitimate skills in one's respected craft (usually in reference to video games). The word is commonly used in video games as a derogatory term.
After having killed a person in any particular video game 8 times in a row, one might say, "Do you like that pwnsauce I keep shooting all over your face?" or, "Awe man, my pwnsauce is getting all over the floor."