Idiom: To go overboard – to be very enthusiastic; to do or say too much because a person is too enthusiastic about something; to do something in an extreme or excessive way.
Context #1 – Two friends are talking at a party
Tina: Did you see Maria? I mean, I know this is supposed to be a dressy party, but my goodness!
Sherri: I know! She really went overboard with all her makeup. No one wears that much makeup, not even models for a photoshoot!
Tina: True. She has so much makeup on, she doesn’t even look like herself!
Context #2 – Two roommates are talking
Susan: Wow! Look at all this food! I thought we were inviting just Jim from next door, not the whole apartment complex!!!
Paul: Yes, I know. Do you think I went a little overboard?
Susan: A little? Paul, we have enough food to feed everyone in the neighborhood for the next week!
Paul: Sorry. Maybe we can take the extra food to a homeless shelter.
Susan: That sounds like a plan.
Paul: Next time, I won’t go overboard!
Meaning: To go overboard means to do or say too much because of being overly enthusiastic about something. In the first dialogue, Maria put too much makeup on for the party. Even though it is a dress party, she should not have put on so much makeup. In the second context, Paul cooked too much food for the one guest they were having over to dinner.