Not only was the alleged native freakishly tall, he was also "dancing, singing, and throwing dust on his head," which is probably a 16th century euphemism for "acting totally stupid." So Magellan and company recorded meeting the world's first tribe of gargantuan naked ravers and, because the world was a "simpler" place back then, everyone just took his word that enormous dirt-heads populated the tip of South America. And they continued to take his word for 200 years. It gets better when you find out that Magellan dubbed this fictional race of huge idiots the Patagons, a name that stuck for the entire area for quite some time. As in, to this very fucking day.
Patagonia: It's like a whole country of Karl Malones.
What really gets our goat is that Magellan probably did meet a tribe of natives on the tip of South America, but they already had a name. They were the Tehuelche tribe and they probably averaged a towering 5'11. That was slightly tall by European standards of the day, but by no means giant. However, when you came back from traversing the great unknown, and all you have to regale the court with are your tales of people who were "kind of tall" and "didn't have an exceptional amount of dirt on their heads," you're going to lose your audience pretty fast.