My sister(14) is trying out for the high school soccer team this week. I (17M) have a lot of friends on the girls soccer team. I asked if she wanted to practice outside then made a joke saying "so you don't look stupid in front of my friends." using a mocking tone to indicate that I was joking. She then got mad and said "I won't look stupid" sounding super offended at my joke. She hasn't played in a couple of years so I thought that suggesting she practice would help and I said the joke because, well I am her older brother its what I do