He developed it in 1974 , spending the summer seeing what kind of beard he could grow .
His giant , walrus - style moustache is McDonald 's most defining physical characteristic and helped him become an iconic figure in the sport .
He developed McDonald 's in 1974 , spending the summer seeing what kind of beard he could grow .
His giant , walrus - style moustache is McDonald 's most defining physical characteristic and helped him become an iconic figure in the sport .