They threw the cup
A thrown cup can be a game or a finished drink. Pick it up once. Offer it again only if they still want a drink.
Once
If the floor is the goal, the cup can wait until the end of the meal. Thirst can be met before they get down.
Picking it up five times teaches a reliable game. Once, then the cup rests.
Drink that fits
Water is the simple drink. Milk stays off when milk is an allergy, in the cup as well as on the plate.
A huge drink just before the meal may be why dinner is short. Notice it for next time.
The food stays separate
A thrown cup does not have to end the familiar food, if they are still eating calmly. End it if the throwing has become the meal.
Stay with them. A cup on the floor and a mouthful of food still needs you watching.
A sentence you can say
“The cup is done. Water was before dinner.”