Why does she mention “saint” here?
Native speaker’s answer
Rebecca
In informal terms, "saint" is used to describe a person who is incredibly giving and altruistic. She makes a joke that because he volunteers with the homeless, he should tattoo "saint" on his forehead (as this is the only way to make it more obvious that he is a good person). Ex: Wow, you donate most of your income to charity? You're a saint. Ex: Yeah, Sandy is a saint. She volunteers at the children's home every week.