I once said "ello govna" to a very chubby man... then i realized how fat he was so i said " oh excuse me...ello CHUVNA". This is used by british people and californians alike. Whenever you see one of your fat friends, just say..."ello chuvna"
(please do not say it if they are sensitive about being fat)
(you can also say it to skinny people to make them feel self conscience about themselves)