A joke

今天看到油價調整了，特地轉個彎去"Shell"加油，我拿了收藏一個月的折價卷(Thanks, come again $2.00 off next oil change with this receipt )給店員要他打折，他卻說"You can get a discount  of $2 for changing the oil，but not for the gasoline!"原來，不是汽油加油折價2元，而是換機油!! 唉，真是鬧笑話了!