lol I know you are not older than 19 but you are not so far off, I ALWAYS tried to finished my fights I had in my life by kickin somebody in the nuts, so far I have only seen one guy who took a kick in the nuts and didn't go down, but I have told that story before.
Yep I'm not gonna talk about streetfights because everyone is going go nuts then lol..
But if someone is Alot bigger and you don't think you have a chance.. A huge kick in the nut or grab his shirt pull him against you and simultaneously headbutt for all your worth and hope he goes down.
a Kick in the nuts has better odds though