if someone wants you to buy either fags or alcohol but are too young you have buyers rights which means you take 10% of the amount that you bought and keep it for yourself or give it to someone else.
for example if you buy a 14 year old a pack of 10 mayfair...then you have get buyers rights which gives you the right to keep one and smoke it yourself or if you buy someone a crate of 20 stella you get to keep 2