Alice and Bob have a somewhat antagonistic relationship and but they meet on somewhat civil terms during which time Alice notices some "sauce" is on Bob's face, but instead of telling him about it civilly, Alice (and it's typically Alice) decides to eat it directly off his face.
This is when a woman licks/eats off the face or body of a man (or another woman), usually an uneasy ally or [...] [tvtropes.org]