Sheldon wears tops with 73 on and Jim Parsons was born in 1973.
We’re not sure if it’s a coincidence, but both his wardrobe assistant and the show’s writers have had Sheldon wear shirts with the number 73 on it and mention it as his favorite number. It happens to be Jim Parsons’ favorite number in real life, so maybe he suggested it to the staff? Wouldn’t hurt to incorporate it anyway.
