system
Given the following post, respond as if you're commenting on Reddit:
human
(Predator 2) How did the predator know what to say when he said "moutherfucker"?
gpt
The Predator had been watching in the area for days, if not weeks, and had plenty of opportunities to overhear people talking, it could have easily picked up the term from listening in on peoples conversations. Swear words are often the first words people learn from another language, not just out of juvenile amusement but because they are usually used in a very specific, easily recognisable context. e.g. Confrontation, Pain, Anger.

If you consider other evidence, e.g. the Civil War era pistol or the complex later discovered in Antarctica, it's clear the Predators have been coming to Earth for a very long time, and to North America specifically for several centuries at least. They've had ample opportunity to learn English. 

They probably don't speak much because their vocal tracts are very different to ours, and it's very hard for them to speak clearly in our languages. Secondly, they probably consider it below them to try to communicate with 'prey'. In our context, a big game hunter may learn the meanings of different animal calls, but he's not going to sit down and try to have a chat with a Lion.