Chinese Have 4 Distinct Tones

In taking Chinese lessons, it's becomming very clear to me that I have a limited range to my voice. In English, what this means is that I am able to say sarcastic things and people have no idea whether I'm serious.  In Chinese, this means I can't pronounce the words correctly.

To properly speak Chinese, you need to clearly distinguish between the different tones (there are 4 distinct tones) in order to convey the word you're trying to say.  If you use the wrong tone, you could be saying something else completely.

This truth is causing me trouble because I don't have a natural rise and fall to my voice.  But it also makes me really curious about sarcasm in Chinese.  Do they have it?  Since the tone of voice is typically what marks it, it would seem that it's impossible to use it in a tonal language.

If that's the case, then people must be so much more sincere.  They must not be able to say, "I'm fine," in a flat tone when they really don't mean it.  They must be more honest with each other.

Then again, there are probably ways to bend the truth in every language.