The tall, sturdy boy clumsily made his way through the crowd, and everyone affectionately called him bullcalf.

bullcalf 是由 bull（公牛）和 calf（小牛）组成的复合词。bull 指成年公牛，calf 指小牛犊。 bullcalf 字面意思是"公牛犊"，在这里用作昵称，形容男孩像小公牛一样高大强壮但动作还不太灵活可爱的样子。