They just speak with tongue in cheek.
他们只不过是说说而已。
speak with tongue in cheek直译过来就是：“面颊上带着微笑说”，这个短语的正确意思是：“说说而已，假心假意地说”。因此，当美国人说"They just speak with tongue in cheek."时，他/她要表达的意思就是:"They are just saying that."、"They just talk the talk."、"They just pay lip service."。
情景对白：
Benjamin: Why are you still looking so depressed since we will finish the project tomorrow?
本杰明：明天项目就完工了，你怎么还这么沮丧啊？
Terry: They said they will perform agreement, but they just speak with tongue in cheek.
泰瑞：他们说会履行协议，其实只不过是说说而已。
搭配句积累：
①How can you fall for it?
你怎么能信以为真呢？
②It is the perfect expression of denial.
这是最好的拒绝方式了。
③You should be tactful in dealing with everything.
你以后处事应该圆滑点。
④Learn how to discern and develop true friends.
学会辨别真假，交些真正的朋友吧。
单词：
1. fall for 信以为真
It's even easier to see how self-employed people fall for this happiness killer.
自由职业者更容易上这种幸福杀手的当。
only a credulous person would fall for that old trick.
只有轻信的人才会被那个陈旧的骗局骗倒。
2. tactful adj. 圆滑的，老练的
If you complain to the boss, be tactful. Don't lose your head.
如果你向老板抱怨的话，要圆滑点。别失去理智了。
She get them to accept these change by tactful management.
她以圆滑的手腕说服他们接受这些变动。
3. discern vt.识别，辨别
It is often difficult to discern the truth of an event from a newspaper report.
要从报纸的报道上去辨明一个事件的真实性很困难。
You need a long series of data to be able to discern such a trend.
你需要一长串的数据才能看出这一趋势。
