The best thing since sliced bread

The first commercial bread slicing machine was invented by Otto Frederick Rohwedder in 1928. A jeweller as well as an optometrist, Rohwedder used his skills to develop an automatic bread slicer. He sold it to the Chillicothe Baking Company. 

Historians suggested that today's popular saying “the best/greatest thing since sliced bread”（最棒的東西 ／事情 ／人）may come from a newspaper advertisement made by the baking company in 1928: 

“The Greatest Forward Step in the Baking Industry Since Bread was Wrapped a fine loaf sold a better way SLICED.” 

With this new invention, the bread was sold in uniform and thinner slices. People found it more convenient and ate bread more frequently. 

Eventually, similar expressions appeared in the baking industry. In 1934, Bell Bakeries’manager promoted the new Bell Vitamin B white loaf.

“This is the most progressive step … since sliced bread was introduced, …” 

Richard Bernard“Red”Skelton, an American comedian, is believed to be the first one to make the expression popular. During a 1951 interview, he described television as “the greatest thing since the sliced bread”. 

Note that this phrase sometimes can be used in a humorous or ironic sense. 

Wow! This new mobile phone is the best thing since sliced bread! 

The winner of the singing contest is so boastful. She thinks that she is the best thing since sliced bread.