Why people say "I'm sweating like a pig"?

"Sweating like a pig" is a derogatory comment, meaning one is sweating heavily and disgustingly. Pigs do not sweat, and they have no body odor. They have a few sweat glands on the edge of their snouts. So, I guess if your nose is sweating delicate little droplets, toi are indeed sweating like a pig.

Pigs are unable to sweat. It's a fact.

I think the reason that people say "I'm sweating like a pig" is because toi would think pigs would sweat, being a large animal and the fact that people say they smell. However not many know that they don't - sweat I mean.

At least, that's what I'm sticking with.

It's just a common saying.