Builder on the third floor forgot to bring his saw up with him, he shouts down to his mate but he can't hear him. So he does sign language. He points to his eye (i) his knee (need) and moves his hand back and forth in a sawing action.
His mate pulls down his trousers and starts pulling one off, "what the hell are you doing" he shouts as he races downstairs. "I said I needed a saw" he said to his mate. "I know" his mate said "I was just lettin you know I was coming"