Backseat buyer is a person who gets excited over other people's future or current purchases. Backseat buyer enjoys helping other person choose stuff as much as buying something for himself/herself. Usually an enthusiastic shopper for themselves as well. It can also be used as an adjective and verb.
“后座購物者”會因為他人即將要購買或現在要購買東西而感到興奮。他們喜歡幫助別人挑選東西,對他們而言,幫別人購物和給自己購物一樣快樂。他們自己通常也是狂熱的購物者。“后座購物者”的動詞形式是“后座購物”,即backseat buying。
Example:
Whenever I think about getting a new gadget, my father goes backseat buyer.
每當我想買一個新玩意兒,我爸總是要做我的“后座購物者”。
If you don't stop backseat buying right now I'm going to smack you.
如果你再不馬上停止“后座購物”,我就要給你一巴掌了。