come out of shell
come out of (one's) shell
To become more outgoing. Usually said of a shy or introverted person. Wow, Anna has really come out of her shell lately. I remember when she wouldn't even talk to anyone, and now she's likely to be voted "Most Talkative."
come out of one's shell
Fig. to become more friendly; to be more sociable. (Alludes to a shy turtle putting its head out of its shell.) Come out of your shell, Tom. Go out and make some friends.