"A slice off a cut loaf is never missed."-WHAT DOES THIS IDIOM MEAN?

In a ual context, it could be used in at least three ways: an attempt to persuade someone to have ; to excuse oneself for having again or for cheating; to soothe the ruffled feathers of a friend whose sweetheart was caught cheating. I don't believe any of the three are intrinsically bashing non-virgins, but they could probably be used that way.