Step chair Puns

Dad had a joke he would pull on us then any kid we would bring over. He would announce that he was going to demonstrate how to pin a cup of water to the wall. He would get a cup of water and a strait pin then move a chair over by the wall. He would then proceed to get his victim to hold the pin and the water while he climbed on to the chair. "OK, give me the water!". Then he would make a show of picking out a place to pin it. "Now give me the pin." When they step up to hand him the pin.... he threw the water in their face.