Towards the beginning of the film when Arthur drops in on Merlin, he asks politely for sugar in his tea. Merlin claps and the sugar bowl marches to him, who gruffly reminds him that guests are to be served first. He goes to Arthur and sprinkles in spoonfuls of sugar until Arthur says "when". He then proceeds to Merlin to give him some. Unfortunately, Merlin becomes distracted with talking to Arthur about academics and other education and is outraged to see the sugar bowl has been spooning a small mountain of sugar into his teacup without being told to stop. He shouts out "WHEN!" in frustration, causing the sugar bowl to run and hide behind the teapot, while Merlin scoops the mountain of sugar out of his teacup and sweeps the rest off the table with his beard. When Arthur reaches out to touch the sugar bowl, the bowl slaps his hand with the spoon.
A moment later as Merlin is magically packing to leave his cabin, the silverware shoots through the air to join the line, but the sugar bowl is delayed when he has to go back for his top and spoon, which were accidentally knocked off by the teapot. He then flies ahead and brusquely cuts into the line, elbowing and thwacking the teapot with his spoon to make room. Merlin abruptly halts the procession and chastises him for being so rough. He gives the teapot one last hit before the line continues and Merlin finishes packing.
That night, when Merlin is put up in the guest tower of Sir Ector's castle, there is a thunderstorm. The tower is found to have a dreadfully leaky ceiling. As Merlin places pots and cups under leaky spots, he also does so with the sugar bowl, who is promptly filled with water. He frantically scoops it out and indignantly replaces his top.
He is never seen again for the rest of the film.
Merlin scolding his sugar bowl
Serving Wart sugar
Over filling Merlin's cup with sugar
The sugar bowl running away after Merlin shouts at him
Apparently the sugar bowl doesn't like to be touched.