西瓜你个萝卜头
[xī guā nĭ gè luó bŭ tóu]
'Watermelon, what a radish head!' This nickname conveys a playful or teasing tone. It's like calling someone 'silly' or 'absurd,' with the added whimsical imagery of being confused enough to call a watermelon a radish head. It might also imply that the person is very naive, silly, or different.