The act of illegally downloading copyrighted material. Piracy. Often used as a euphemism on forums where you can't explicitly talk about piracy
"fuck, I really want to watch that dogshit little mermaid remake, but I don't want to give those slimy crooks any money" "just Yarr harr it"
"Dude, how did you get so many games? you must be rich!" "Nah man, just Yarr harr'ed it