Well, they don't celebrate it. It's considered a very pagan American holiday (which is pretty much what it is, except I think it originated in England). Still, you can find a few Halloween decorations and costumes in large stores and probably some teens "celebrate" it in bigger cities.
We always do something at home, since there's no trick-or-treating. A couple of years ago the kids had a party and invited friends from school. They were all so confused when they saw Evie dressed as a ballerina. Ballerinas aren't scary! They thought you have to be something frightening.
As I say, I always try to do something Halloweenish. This year we did the usual stuff, but the kids made almost all the preparations.
"We" carved a pumpkin: Greg (who hates Halloween) did the artistic part, the kids scooped out the "monster teeth" (all while I took a nap). Note the little hanging decorations the kids made a few days ago for the stairs.
We played Halloween Bingo by candle light: the kids drew the pictures on the cards (spiders, witches hats, eyeballs etc.).
We played with slime: I just put the potato flour and water and bowls on the table and let them make it for themselves (no green food coloring or anything).
As usual I hid the candy around the living room and they searched for it by candle light.
Then we watched The Legend of Sleepy Hollow and ate dirt dessert with worms.
And there you have a lazy mother's Halloween.
As a heavily (95%) Catholic country, they celebrate All Saints day on November 1st and the Day of the Dead (not sure if that's what you call it in English) on the second. This is a very lovely holiday when everyone visits the graves of their loved ones. The cemeteries are amazing, all lit up with hundreds of candles. Even though we live far from the graves of any family members, we always visit a nearby cemetery just to walk around. It's magical. Here's proof (from a few years ago):
It's also a big drinking holiday (any excuse will do in Poland :), and as it falls on a Sunday this year we'll be staying off the roads, meaning no going to church. This is one of those holidays that they give statistics on the news every night about how many drunk drivers were stopped etc.
But those cemeteries are gorgeous.