Be anyone's slang
Be very likely to accept sexual or amorous advances from anyone.
He had made advances to that girl when she was drunk, but she told him she wasn't anyone's.
I think she will agree to have sex with you after three shandies. She's anyone's!
The origin of this slang is not clear.
Stupid or crazy
He is definitely not the full shilling when wearing a thick coat in this sultry weather.