my girlfriend is polish and irish, she wants to get a tattoo incorporating both of them something with a shamrock and something to do with poland combined, does anyone have any kind of idea of what to merge together for them?

I would steer clear of anything like shamrocks or leprechauns. Being Irish I wince whenever I see these kinds of tattoos. They are usually done by people who are not really Irish, are third or fourth generation or WANT to be Irish.

Either way they look cheesy!

You could do some research on Irish river gods or mythological creatures and then do the same for Polish ones and maybe try to incorporate the two.