Is it okay to fight dirty? (Poke the eyes, strike the groin, etc)?

You are legally obligated to using the least amount of force that's necessary to end a clear and present danger.  Crippling and maiming techniques fall into the "lethal force" category in a lot of jurisdictions, so unless you can convince a jury that you were afraid for your life, it would be hard to justify using some of those techniques.

Frankly, a good knockout punch has the same result (ending a threat) without a lot of the legal complications.

It's not that certain techniques are "dirty" (really no such thing outside of a sport contest) but they might not be appropriate to use, depending on the circumstances.

And frankly, strikes to the groin are overrated.

Fighting for your life, sure; in a point-sparring TKD match, no.

Only if your parents tell you that it's ok.

***** if you want to do all that, don’t act surprised if somebody start bussing a cap in yo dumb ***. 

No, its just like an animal