Hi Sam, it seems there are two spellings for Badte-maru. The official one seems to be Badtz Maru, with the “z” at the end of the first name.
In Japanese, “badtz” (batsu) is a term for “X”, the cross signifying a wrong answer. “Maru” means circle or “O”, and signifies a correct answer. Thus, his name figuratively means “wrong-correct,” and is frequently represented by “XO”. (Wikipedia) http://en.wikipedia.org/wiki/List_of_Sanrio_characters
Digital Citizen 
what does badtemaru mean plz help !!!!!!!!!!1!!!!!!!!!!!!!!!
Hi Sam, it seems there are two spellings for Badte-maru. The official one seems to be Badtz Maru, with the “z” at the end of the first name.
In Japanese, “badtz” (batsu) is a term for “X”, the cross signifying a wrong answer. “Maru” means circle or “O”, and signifies a correct answer. Thus, his name figuratively means “wrong-correct,” and is frequently represented by “XO”. (Wikipedia)
http://en.wikipedia.org/wiki/List_of_Sanrio_characters