What is a comical switching of first sounds words?

A comical switching of first sounds in words is called a spoonerism.

Here are some examples:

* "You have hissed all my mystery lectures" instead of "You have missed all my history lectures."

* "Is the bean dizzy?" instead of "Is the dean busy?"

* "I'd like to have a little bit of a blushing crow" instead of "I'd like to have a little bit of a crushing blow."

Spoonerisms are often unintentional and result from a slip of the tongue. They can be funny because they create nonsensical phrases that sound similar to the intended words.