This is someone who gives you a gift, usually a gift certificate at a bar or restaurant, with the intention of you using it with them, so in effect, it is only a half-gift
Danny: Happy birthday, Mike, here's your gift!
Mike: Hey, a $50 gift certificate to Rob's Good Time Bar, thanks!
Danny: What are you doing today? I was thinking of going to Robs, wanna go?
Mike: Ummmm, yeah, I guess...(wow, what a cheap fuck Dan is, he is the half-gift giver, looks like I'm paying for the tab, ... again...)