The word exclaimed when a particular individual in a group makes shit banter whilst trying to be one of the lads. A vertical arm sweep/cutting motion is made at the same time, in order to portray a separation or screen between the person who made shit banter and the person calling "bellini".
Danny: "lads you seen the tits on mrs roberts? she may be a cow but I would milk those udders, know what I mean?!!"
Member of "lads": "Bellini".
Initial conversation continues.