Mr. Bean: The Animated Series

Mr. Bean and the father-and-son compete for the incoming biggest watermelon contest. Thanks to the super light lamps, Mr. Bean's watermelon grows heavier until the father and son decides to put eating bugs in Bean's watermelon. Then, when they saw Bean with his watermelon, they wanted to swap their watermelon with his but failed to realize that the eating bugs are inside. So Bean convinced the judge that the watermelon he's holding is his and wins the trophy dropping the watermelon on the old lady.