throw sth in
(a) include sth with what one is selling or offering, without increasing the price (出售或出價(jià)時(shí))額外贈(zèng)送某物
You can have the piano for 60, and I'll throw in the stool as well. 這架鋼琴可以賣給你 60 英鎊, 琴凳我奉送.
(b) make (a remark, etc) casually 隨口說(shuō)出(話語(yǔ)等).