I am in Germany and looking to make a trip into Poland to buy 100 cartons (20,000 cigarettes)
Believe it or not, there exist limits on transporting legal drugs (tobacco and alcohol) within the EU.
ec.europa.eu/taxation_customs/individuals/travelling/within-eu_en
Not sure how this works in practice, but with a 100 cartons, I would imagine if you ever get stopped and checked by the Customs Police you will no doubt be questioned and will have to convince them that it's all for personal use (good luck with a 100 cartons in your boot), otherwise probably a (hefty?!) fine will be imposed.