Hawaiian

Hawaiian is the traditional language of the indigenous people of Hawaii Islands.

Appearances in The Big Bang Theory

 * In The Luminous Fish Effect (S1E04), Sheldon uses the Hawaiian word "mahalo" ("thank you"), and tells Leonard that there is only eight consonants in Hawaiian language.
 * In The Boyfriend Complexity (S4E09), a drunk Raj uses the word "mahalo" when he calls Hawaii only for a joke.
 * In The Vacation Solution (S5E16) Sheldon uses the word "mahalo" again when Leonard proposes that he takes his vacation in Hawaii.