Why is Liu Liang called Liu Tou?

Liu Liang's head is big. In the TV series Imitation of Stone, Liu Liang is the boss who sells cloth. Because he is bigger than normal, his neighbors affectionately call him "Liu Tou", and he acquiesced in this nickname. "Imitation Stone" tells the story that a family can hold its own in this colorful world like a stone in a very turbulent era.