How big is the chance of getting into the US if I beg/talk nice to them at the custom if my mom and dad are with me?
0%

You've been formally denied TWICE. That means you're not going to be allowed in, and if you come on over anyway and think you're going to sweet talk your way in, you're going to find yourself turned around and sent right back home.

Save your plane fare. Stay home. Come visit legally once you manage to obtain the proper visa.