When is a typo not a typo? According to Web site for International Talk Like a Pirate Day (September 19th of every year), Arrr is anything but. In pirate lingo, it’s one of the “five basic words that you cannot live without ... if you just want a quick fix, a surface gloss, a ‘pirate patina,’ if you will.” The definition continues:
This one is often confused with arrrgh, which is of course the sound you make when you sit on a belaying pin. "Arrr!" can mean, variously, "yes," "I agree," "I'm happy," "I'm enjoying this beer," "My team is going to win it all," "I saw that television show, it sucked!" and "That was a clever remark you or I just made." And those are just a few of the myriad possibilities of Arrr!
A search of the OhioLink database does in fact reveal some legitimate entries for Arrr! and Arrrgh! But Arrr* is also a typo found in words such as arranged, arrangement, and arrow. There are currently 11 instances of it in records for English-language materials, and it’s categorized as an error of moderate probability on the Ballard list.
(Pirate, from Wikimedia Commons)