What NOT to say to a girl

Today at work we were repackaging shoes and I went to throw and old box into the gaylord (big box) and my supervisor Christian, a big antagonist I might add, hit it away from the gaylord so it wouldn't go in. Sarah, a girl I was working with, said, "OOO, rejected!" And Christian in response said something to the effect of, "Ya, just like all the other guys in your life!" I was shocked. Sarah and I stood there with our mouths agap. I couldn't believe he said that! It seriously made me feel about this big (imagine me holding fingers an inch apart). Talk about one of the biggest no-no's to say to a girl. Take notes, boys, take notes.