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

It’s a sport ?. . 

Depends on the situation. If you're being attacked by a psycho in the street, who you don't know, then fight dirty.

If you're fighting some guy that you do know because you two don't get along and you want to know who's got bigger balls, you really shouldn't fight dirty. 

It self-defense vs. a friendly fight. 

There are really no rules basically in a street fight and so that being I don't see anything wrong with fighting dirty per say.  Poking the eyes, kicking or striking to the groin, pulling hair, biting, I see nothing wrong with really.  There are however some things I would not do or consider doing not because they are dirty but instead because maybe the situation does not call for that level of violence.  Picking up a brick for instance and caving in somebody's skull is and example of what I am referring to and something I would not consider unless I really wanted to seriously hurt the other person or kill them.

Dumb question____________

In a life or death yes in the ring no!

yes you do whatever to try and win

If you're fighting for your life, I'd say yeah.  Just a stupid fistfight between drunk idiots, there's a code of honor.