I am a senior three boy. Let me take off my coat and show her what my upper body does.
You are a senior three boy. I want you to take off your coat and show it to her. what do you want to do? That is to say, your seniors see that you have a good figure. I wanted to make a boyfriend with your two friends, so he took off his coat and looked at your upper body for the first time. If you take it off, next time he wants to see other places, this is your senior sister's idea.