out of your depth
Meaning: If you're out of your depth, you're in a situation that you don't have the experience to handle, or the knowledge to understand.
- If it hadn't been for all the advice her friends had given her, Jodie would have felt a bit out of her depth on her first date.
- I'd only been a policeman for a couple of weeks, and here I was trying to talk a guy out of shooting his family and himself. I was totally out of my depth.
I knew I was out of my depth when