The exact origin of the name "Texas sheet cake" is not well-documented, and there are several theories about how it got its name. One theory is that the cake is called a "sheet cake" because it's traditionally baked in a large, flat, rectangular sheet pan (often 18x13 inches) with raised edges. The size and shape of the cake are ideal for serving a crowd, which could be associated with the idea of Texas and its reputation for everything being larger than life.