What are some examples of onomatopoeia in a sentence?

(Onomatopoeia includes Words based on natural sounds, or the sounds themselves.)

"He was certain that he heard the buzzing of a fly in his room."

"There was a loud boom as the plane broke the sound barrier."

"Whenever a stray dog came near, the cat would hiss and arch its back."

"He said 'Shh!' and hid behind the door."

(see related question)