1) Any of many fluids secreted by the human body, and which accumulate on surfaces which should be kept clean of such residues. Often requires prefixes to clarify origin (e.g. "handsauce" or "rumpsauce")
2) Any fluid that leaves a grimy residue.
Man, there's earsauce all over your cell phone!
Which one of you choads splattered facesauce all over the bathroom mirror?