UB40 Singer Ali Campbell Red Wine and Nipple Rings!

Former UB40 singer Ali Campbell let it all hang out in New Zealand this weekend ... by going topless in public.

While holding a glass of what appeared to be red red wine, the 53-year-old flashed his buxom man breasts on a balcony in Auckland.

FYI -- UB40 released "Red Red Wine" back in 1983. Unclear if he was still rockin' the nipple ring back then.