Wheat paste is an extremely inexpensive and easy-to-make adhesive that protesters often use to paste up flyers. The key thing about wheat paste is that once applied, it is very difficult to peel off, so pieces of your flyers are guaranteed to stick around for a long time.

These instructions are adapted from some Canadian protest websites:

MAKING PASTE - The easiest way to make paste is to mix flour and water together. You mix the flour and the water till the mixture becomes just like slightly thick pancake mix. If the mixture is too watery it will take a long time to stick to poles, if it is not watery enough it will be hard to use. The best way is to experiment with a small amount of paste and see what proportions are the best. Usually 1 part water to 2 parts flour. (YMMV)

PUTTING UP THE FLYERS - Put the paste in some kind of a bucket. Bring a stick with you to keep stirring the mixture. The next thing you need is a paint brush, the wider the better. First you dip the brush in the paste and cover an area on the pole that will be big enough to put the flyer on. Then you stick a whole bunch of flyers to the wet surface, maybe 3-5 at a time. Next you dip the brush again in the paste and cover the whole stack. Be sure not to miss any of the corners, if you do it is easy to take the flyers off. Make sure to apply enough paste to soak through the paper.

By pasting several sheets together, you make it that much tougher to remove. When some capitalist pig comes along to remove your propaganda, the outer layers will tear very reluctantly and in pieces, so the layers underneath will still be visible, proudly displaying your message. While the websites advocate posting flyers only on telephone poles and other pieces of public property, I have been to meetings where they tell you to wheat paste the flyers to windows of private establishments to enhance the effect. Judge this as you will.