Waltz
Leela doesn't do ballroom dancing. Romana diplomatically points this out when Narvin requests Leela as his partner for the dignitaries' ball, but she eventually agrees anyway.
Narvin leads in the dances, an unhappy Leela following as best she can, and they smile into one another's faces and snarl dire insults under their breaths. But it all pays off when the assassin, whom Narvin's been baiting for weeks, tries to stab him in the back.
"There, you see?" he says later to Leela as she cleans the blood off her knife. "There was a reason I brought you."
She actually smiles.