In the episode That's Show Biz, Marina Ryan is a USO showgirl who needs an emergency appendectomy. She falls in love with Hawkeye, who does his best to not encourage her. The following is a conversation between Hawkeye and Marina.
Hawkeye: "I've seen too much ever to be wide-eyed again. We're the wrong blood type. We don't match. Innocence-positive and lechery-negative."
Marina: "Let me stay. I'll prove you're wrong."
Hawkeye: "No, no. It's not worth the risk. Remember, you did ask me not to leave a scar."