My husband tells the story of his mother giving him the task of cleaning something when he was a kid. She said " and use some elbow grease on it". Some time later she came in the kitchen and there he was going through the cleaning products under the sink. She asked him what he was doing and he said "looking for the elbow grease." Thinking he was making fun of her, she "gave him a friendly tap". She thought he was mocking her. He thought there was something called elbow grease, after all she used bacon grease when cooking. A review of the meanings is good! Thanks.