Some lady's think of themselves a "the mama" The desired woman. So, its just a slang expression come here, I want to be with you. I want your body. Come to mama.

It's a slang term that comes from something like a mother talking to their baby or young child. An infant might be learning to walk and the mama will be saying, "come to mama," to convince the infant to come to her. When used outside of that context, the situation will determine the meaning. However in my experience, it is received as being annoying with adults or older people. It invokes the same mother child "idea" in a condescending way, as though they were your mother. Understand it's origin and you'll get it.