In England, if you skip to the front, it's sacrilege.
I suppose it is not England though! :-)
In Poland I suppose you have to do as the Poles do, if you can't beat them join them. If you lose 10 minutes to someone jumping the queue you should skip the queue the next time in the same shop, don't take any notice of complaints, pretend that you don't speak Polish etc., you can't feel bad for it as you are only balancing thing out. Tell them that they are wasting more time just arguing with you, better to let the American etc. go first.
Shop assistents etc. have no time for customers normally so they are not going to care about a bit of queue skipping.