"Yaroo" on the end of bakayaro makes the "baka" part a bit more vulgar. It is like calling someone a moron, idiot, ***hole, if you get the drift. If I am not mistaken, the "yaroo" is from the verb yaru which is a very familiar form of the verb suru (which means "to do" in Japanese). The familiar form, and the conugational tense implies that the person referenced is willfully being a jackass and making a spectacle of himself. The vulgarity is highlighted by verbally calling attention to the person for his actions, and potentially bringing him a loss of face due to your implication. It is a common way to put someone down or 'dis' them for their actions. You might also like to know that the "ba" comes from "horse" in the Chinese characters, and "ka" comes from "deer", although the common written form today is to use the simplified hiragana writing system, rather than the Kanji form. However, because of the meaning of the two characters, the statement also indicates that the person is like the misbegotten offspring of a domestic and a wild animal, which makes him utterly useless and ignorant.

Mercury retrograde is the act of taking a shit whilst mooning one or more human beings. Your day can typically being going well, according to your horoscope, until you are forced into witnessing Mercury retrograde. Performing Mercury retrograde will often speed the astrological cycle forward for the individual performing the Mercury retrograde, bringing about happy and fruitful times to come.

A slightly harsher version of the word baka, wich means idiot, or fool. Also can be translated as: asshead, asshole, dumb-ass, fool, goose, moron, old socks, simpleton, and most recently, ‘you goddam simp!’

moron, asshole, stupid, idiot. The more vulgar version of baka.

Bakayaro is a common nickname used in Japan. It means something like fucking ass-hole or you are a mother fucking bitch or whatever.