French kiss kissers

OPENMOUTHS

Think about what’s needed when two sets of lips fully meet in a passionate embrace.

"French kiss kissers" plays on the idea of what you actually do during a French kiss—you keep your mouths open. The clue hints at the physical action rather than naming the people involved, so the answer describes the state of their mouths. "Open mouths" fits perfectly as a literal two-word phrase, but crossword answers often omit spaces, turning it into the single word OPENMOUTHS. The humor comes from framing the answer as a trait of the kissers rather than the kiss itself.