18-year-old Louis is apparently a 'clean freak' and often opts to stand on his hind legs when he carries food to keep it away from the dirt and mud.
'Some gorillas will walk upright when they have their hands full,' says the zoo’s curator of primates and small mammals, Michael Stern. But he admits it is more unusual.
'He can often be seen walking bipedal when his hands are full of snacks...so he doesn't get his hands dirty!' the Philadelphia Zoo posted.
While people were quick to label Louisa a 'germaphobe', Stern said the tidy gorilla wouldn't understand germs, and it's more about avoiding mud.
'I would guess it’s the feel of the mud. They’re rainforest animals and they’re built to deal with mud, but they all have their own personalities,' he told National Geographic.
The zoo even rigged a bridge made of fire hoses that Louisa can use to avoid muddy puddles in the enclosure.
'When caught out in a rainstorm, he'll run bipedally across the yard to seek cover, and when he accidentally steps in mud, he'll find a leaf or a paper bag and wipe his hand or foot off until they are clean again,' a blog post for Philadelphia Zoo said.
Weighing around 200 kilos and standing at six-feet tall, Louis might look intimidating, but he's said to be the shyest gorilla at the zoo.
Since the video of Louis was posted online, he's become an instant star.
'Put some clothes on him, open the gates, no one will notice,' one person quipped.
'I don't blame him. Much easier to use both hands to hold more snacks if you're walking on two legs,' said another.