This is one that can benefit you as much as him. If you don't tell him what you like, he's just flying blind. In fact, if you haven't complimented him he might even think you don't like what he's doing. And of course, the more you tell him you love it when he scratches your lower back, the more he'll do it。
这是一句让双方都开心的话。如果你不告诉他你喜欢他哪一点，他就不会知道。实际上，如果你不赞美他，他甚至可能觉得你不喜欢他正在做的事情。当然，你越是跟他说你喜欢他怎么做(比如搂着你的腰)，他越是乐意这么做。