(noun) a liquid or semi-liquid edible dressing or condiment served as an accompaniment to or an ingredient in a meat, dessert, or other food: pizza sauce, steak sauce, cranberry sauce, chocolate sauce, etc., or (verb) to add said sauce to something.
(noun) an intoxicating substance, usually hard liquor.
(noun) A word used to describe something as especially good, often used stand alone as an interjection.
(interrogative) slang for "source"- usually used when asking for the source a particular file on a "chan" or other chat/image board.
(archaic- now usually only heard in old Tom & Jerry or Bugs Bunny cartoon reruns from the '40s) rude or impudent speech, especially applying to "backtalk."
"This pasta needs more marinara sauce."
"I threw back way too much of the sauce last night- I can't remember getting this new tattoo."
"I just banged Eddie's hot sister! Sauce!"
"teh girl pwns! I need moar! Sauce?!"
"Don't you young whippersnappers give me no sauce, dagnabit!"
Zach is stupid-SAUCE.
Homework on a Friday? That's so weak-sauce!
The sauce is very important. As Sizzles law of attraction states: a physically attractive woman who has no sauce, is less attractive than a physically less attractive woman with the sauce.
For an analogy: You could have some of the best egg noodles with no sauce, but they won't be nearly as good as some ramen noodles with awesome sauce on them.