I searched for the meaning of "take in", and the dictionary showed me several meanings.
- to understand
- to receive into one's house in exchange for payment
- to accept
But the sentence below which shows 'take in one's sign' form and I guess that is a kind of phrase, but I don't know what that means.
Here is the part, which is from 'Baker's blue-jay yarn' by Mark Twain.
A jay can cry, a jay can laugh, a jay can feel shame, a jay can reason and plan and discuss, a jay likes gossip and scandal, a jay has got a sense of humor, a jay knows when he is an ass just as well as you do - maybe better. If jay ain't human, he better take in his sign, that's all.