George Thorogood and the Destroyers were a blues rock band that started in 1977. Their classic hits Bad to the Bone, and One Bourbon, One Scotch, One Beer, are probably some of your dad's favourite songs
The tee appears to be from the late 80s, as the Album Born to Be Bad was released in 1988. The tee is tagged Medium on the Screen Stars tag, fits more like a small.
pit to pit - 17”
length - 28”