Today, the term bookie  is slang for baby  or sweetheart.  People often refer to or call their significant others bookie  to say, Hey, I like you.  Basically, it's a placeholder for their name. Take a look at these examples: Bookie, you're the sweetest girl I know. 
The legality of bookmaking varies from state to state in the US. While some states have legalized sports betting and have established regulations for licensed operators, others still prohibit it. Running an illegal bookmaking operation has severe legal consequences, including fines and imprisonment.