Everything on this page with regards to origin is BS. This word is a latin phrase, therefore it is as Italian as it is Spanish. I have known this expression since I was a kid and it is used in Spanish very very often, same goes for "Forget about it"
McDonald's will state "ba da ba ba ba" is only a catchy jingle. BUT. it may be some sort of secret hypnotic tone, or satanic chant...If they are part of some satanic cult...Much like Ab Bra Ca da Bra was originally a healing chant!