The Clue "Oh, forgot 2 mention ...", in text
The Answer BTW
The clue "Oh, forgot 2 mention ..." suggests that something important was left out of a conversation. The abbreviation "BTW" stands for "by the way," which is often used when adding extra information. It fits perfectly because it indicates that the speaker is introducing a new point they previously overlooked. Using "BTW" helps keep the conversation casual and friendly.