A person who keeps close track of giving and/or receiving. If they give you something, then you automatically owe them something of equal or greater value. If you give them something, then they feel obligated to return the gesture. "Scorecard givers" don't understand that you aren't supposed to "keep score" of giving! See asshole.
I bought him lunch yesterday, so today he was obsessed with buying me lunch. What a scorecard giver!