Voi a word said by Squalo Superbi in Hitman Reborn
he usually says voi with having the most emphasis on the o part such as: "VOOOOOOOOOOOOOOOOIIIIII!!!!!!!!!!!!!"
A common greeting used for sharks, A.K.A. Squalo Superbi. It usually make Yamamoto orgasm whenever he hears it, which in turn pisses Gokudera off.
It is also very annoying and scares the living crap out of everyone that hears it.