That old professor is such a stuffed-shirt, he even criticizes students for wearing jeans to class.

stuffed-shirt 是一个复合名词，由 stuffed（填满的）和 shirt（衬衫）组成。字面意思是"塞满填充物的衬衫"，比喻那些过分正式、古板、自以为是的人，通常用来形容那些死守传统、缺乏幽默感的权威人士。