1-The sneaky boy is like a sly fox.
2-The boy is as sharp as a tack.
3-I am as free as a bird, on vacation.
Or On vacation I am as free as a bird.
4-The mom is as busy as a bee.
5-The obvious answer was a plain as day.
6-My fluffy dog is as cute as a button.
7-The tired boy went out like a light.