They can perform sit-ups in order to hear a poem, trade an old CD for a used book, or give a back massage to see a light show with sparklers. You can bring anything to trade, even your dog--they don't get to bring it home, though, they "borrow" it for half an hour.
參加市集的年輕人，可以用伏地挺身來交換對方為你念首詩、用舊 CD 換舊書、或者用背部按摩來換一場仙女棒煙火秀，甚至連自己家的狗，都可以帶來這邊換──不是換給別人養，而是「借」他在現場遛狗半小時。