A proverb saying it is shameful for a man to refuse a woman's advances or invitation; one should not spurn an offered opportunity (often used in a somewhat old-fashioned way).
祖父は冗談めかして「据え膳食わぬは男の恥だ」と言った。
My grandfather jokingly said, "It's a shame for a man to refuse an offered meal (or a woman's invitation)."
昔のことわざだが、彼女の誘いをいちどは受けてみてもいいかもしれない——据え膳食わぬは男の恥、という考え方もある。
It's an old proverb, but you might accept her invitation at least once—there's the idea that "a man who won't eat the offered meal is shameful."