If you rub a balloon on your sweater and then press it to a wall, it will often stick there. Why does this happen?
Rubbing the balloon surface gives it an attractive force. When the balloon is touched to the wall, the wall is attracted to it.
Rubbing the balloon adds a negative charge to the balloon, and this charge on the balloon induces a positive charge on the wall. The attractive force between the balloon and the wall makes the balloon stick to the wall.
Rubbing removes a surface layer of grease, allowing the rubber to come in sufficiently close contact with the wall so that air pressure holds it there.
Rubbing the balloon causes moisture to condense on it, and surface tension causes the balloon to stick to the wall.