The cool way to say "roar"
Originated in the Spongebob Squarepants episode "Pickles" when Spongebob responded an intimidating customer by saying "rawr"
Bubblebass: "I hear Squarepants is back.
Spongebob: I'm right here, Bubblebass.
Bubblebass: I thought I ran you out of town. *spits in can*
Spongebob: This is where I belong. *blows bubble*
Spongebob: Rawr. ;)