"Juwanna Mann" star Miguel A. Nunez Jr. really didn't want to pay for hundreds of dollars of groceries ... at least according to cops, who say he gave himself the ole five-finger discount.
Law enforcement sources tell TMZ ... the actor was checking out at an L.A. Ralphs supermarket this week when his credit card got declined, so he just took his groceries in his cart and walked right out the front door without paying.
Pretty bold move ... allegedly.
Our sources say Miguel returned to the same Ralphs a few days later, but he wasn't allowed inside and cops were called.