What is this pun is based on? “Time flies like an arrow. Fruit flies like a banana!”

Choose the best punning ending: “Two silk worms had a race. They ended up in … .”

I nearly bought a clock today but it wasn't the time. The pun plays on:

Choose the answer that turns the question into a pun. Where do you find giant snails?

Choose the answer that turns this question into a pun. What's the best way to stop a bull charging?

Complete the sentence to make a pun: “I always wanted to be a food taster, but I had too much on my … .

Complete the sentence to make a pun: “My brother always wanted to be a banker, but he lost his … .”

Make the sentence punny! “Broken pencils are ... .”

Make it punny: “Parallel lines have so much in common ...”

This pun is based on an idiom and a homophone: “No matter how much you push the envelope, it will still be stationery.” What are they, and what do they mean?