One who receives a gift from someone, does not like it, so he/she gives to someone else for his/her birthday christmas etc.
Elain accused George of being a re-gifter after she found out that George had given the gift to his girlfriend for her birthday.
A person who gives things they received from others as gifts. They take what was given to them and send it to someone else out of laziness and spite.
Derived from Seinfeld
I think he gave you the same book I bought him for Christmas. He is a damn re-gifter!