A person who gets excited over other people's future or current purchases. Usually an enthusiastic shopper for themselves as well.
Can also be used as an adjective and verb.
"I'm such a backseat buyer; I love helping my friends choose stuff as much as buying something for myself!"

"Whenever I think about getting a new gadget, my father goes backseat buyer."

"If you don't stop backseat buying right now I'm going to smack you."
by lautnitha August 25, 2007
Get the backseat buyer mug.