Alright so.

Why do people in the United States (midwest) look down on me for being Polish.

It's as if we are negros to some folk I swear the jokes just aren't even funny, many say that being a Pole means your stupid...

Can someone explain this mentality to me?
I have tried looking up multiple times why my Polish decent automatically means I am a halfwit and I have not found a conclusion.

Then some will say we Poles are all cowards because we gave up to Germany in WW2..

Any help to this pointless ridicule would be much appreciated.