Can anyone tell if this phrase is right: Zestrat sie a nie Podat sie

My grandfather used to always say this phrase and he said it meant something like **** yourself but don't give up
I asked him to right it down for me so I can get a tattoo of it. I was wondering if it was right. Thanks

Zestrat sie a nie Podat sie

zesraj się, (a) nie poddaj się

Other, slightly different version (but meaning is the exactly the same):

Zesraj się a nie daj się

Hmmm, think twice before doing it...

Cinek

It conveys the notion of 'sh-- in your pants but never give up!'