still waters run deep

(proverb) a quiet person may be extremely wise and intelligent

Example Sentence:

That guy in our class is always very shy and quiet, so I decided to talk to him on the bus yesterday. He was so funny and smart, we had a great conversation. Still waters run deep, I guess!

Similar idioms:

1. beauty is only skin deep
2. smart alec
3. smart ass
4. smart cookie
5. smart aleck
6. devil’s advocate
7. turn into
8. every dog has its day
9. don’t have what it takes
10. one can hear a pin drop
11. run of the mill
12. run out of gas
13. don’t judge a book by its cover