Uncle Si "Hey Jack" Duck Dynasty Hat.
Si Robertson (Silas Merritt Robertson) is Willie's uncle and Phil's brother, a Vietnam War veteran. He works at Duck Commander, making the reeds that go into every duck call. Si is known for his storytelling, his constant use of the expression "Hey!" and the word "Jack" to end many of his sentences, and his ever-present blue plastic Tupperware cup filled with iced tea, which his mother sent him while he was stationed in Vietnam. Si is married to Christine Robertson