Scene 10 What does Blanche say that changes Stanley's attitude from joy to menace?

Blanche makes an innuendo to Stanley that he will not tolerate..... she alludes to him as swine.

A cultivated woman, a woman of intelligence and breeding can enrich a man’s life – immeasurably! I have those things to offer, and this doesn’t take them away. Physical beauty is passing. A transitory possession. But beauty of the mind and richness of the spirit and tenderness of the heart – and I have all of those things. But I have been foolish - casting my pearls before swine!