It is an expression used to ask for something. In Colombia I use it a lot when I want to ask for something, but I don't want to seem demanding. For example, if I want to ask someone to call me at 6 pm, but I'm not giving an order, I say:

Regálame una llamada a las 6 pm

I can change the expression and say:

Por favor llámame a las 6 pm

In a market I can say: "Regálame una Coca Cola", but I am going to pay for this.