Don Gorske (famous for eating many, many Big Macs)

Gorske claims that after getting his first car, the first place he went to was the McDonald's on Military Road in his hometown of Fond du Lac on May 17, 1972.[4][5] He purchased and ate three Big Macs at lunchtime. He returned two more times to consume nine Big Macs the same day he discovered the burger. He further claims to have eaten 265 Big Macs the following month, an average of 8.5 Big Macs daily.

Gorske had a single Burger King Whopper sandwich in 1984 and never ate one again. Gorske tried the Whopper after his friend bet him $5 to do so, later spending the winnings on Big Macs.

That's some brand loyalty.