I don't want to go and that's that.

我不想去，就是这样。

That's that 通常是接在否定句后，意思是，就这样了，不必再多说了。这样的语气是很强烈的，通常听的人可能会不太高兴。有时电话推销员很烦人我也会跟他说 "That's that." 也许一开始你只是很客气地说 "I am not interested." 可是有些人就会不识相地一直说 "What do you want me to do to change your mind?" 这时我就会不客气地说 "I don't want it, and that's that." 通常他就会知道你是真的烦了。

"That's that." 这句话跟 "That's it." 不太一样 "That's it." 的意思是就这样吧，就这些吧，在点餐时会用的到。That's that 则是表示不想再跟对方谈下去了，同样的情况，你也可以这么说 "The conversation is over." 我想这个意思也很明显了。