The Supreme Kek
Ogg literally translates to
kek (which literally translates to lol) on
World of Warcraft. When someone from the Horde side types
kek (when they want to say lol, but in their language) in /say, members of the alliance side see ogg instead. Not specific to Orcs.
Human
Paladin: Dude, that Orc totally just
pwned you.
Orc: Ogg.
Human: Dude, now he's laughing making the supreme kek at you.
Kick his ass.