John Garner was a nutrition adviser from the USDA, who appeared in the Season Eighteen episode, "Gluten Free Ebola". In the episode, he ingests extracted pure gluten, which results in his demise.
Background
John Garner is appointed by the USDA to give a presentation on gluten at the Park County Community Center, in an effort to disprove rumors of its negative health effects. He explains what gluten is and where it is found, putting a lump of dough into a washer to extract pure concentrated gluten from it. Having recently gone gluten-free, Mr. Mackey challenges him to ingest this extract, which he does with initial hesitation. Shorty after, he begins moaning as his body burns and his penis flies off. Upon witnessing this, the audience flees the community center in horror.
Appearance
John Garner was shown wearing a white lab coat over a gray suit, with a white collar purple shirt and a red striped tie. He wore glasses and had light brown hair graying on his temples.