Boundaries at restaurant?

At dinner last night, my 17-year-old daughter was being overly playful with her boyfriend (18) in front of family — hitting him with a balloon on a stick, squishing his face hard enough to cause a small cut, and even putting a flower from her bouquet into his mouth (thus seems disrespectfulgiven he boughtthe flowers).

Other adults at the table were concerned and pointed out safety issues.

How would you handle this kind of behavior — is it normal playfulness, or should I be addressing boundaries with her?