Example sentences from the web:
- A: What do you think of global warming?
B: I don’t know.
A: Penny for your thoughts?
B: Well, if you want to know, I feel like people aren’t doing enough to stop it!
- Noticing his friend was sad, Joe asked, “A penny for your thoughts?”
- A: What do you think about Lisa? Penny for your thoughts?
B: People don’t like Lisa very much because she is always giving her opinion, even if people aren’t asking for it.
A video on this idiom by Englishcafe: