First, read the original XKCD comic.
This Python script will generate passwords (or rather, pass phrases) such as the one in the comic. They need to be generated with a computer; humans are hopelessly bad at coming up with a random sequence of words.
Invoke it from the command line, like so:
$ python3 chubs.py 64 some-long-text-file.txt
5640 unique words in 1 files (12.5 bits per word)
Requested 64 bits; these 6 word(s) have 74.8 bits:
tall healthy disagreeable noble connect perplexity
The words will be randomly selected from the set of words in the text file listed on the command line. Pick any text file you like (or files---you can list as many as you like). This example uses Jane Austen's Pride and Prejudice from Project Gutenberg.
The numeric parameter you specify is the number of random bits used to create the password. This is a measure of the password strength relative to an attacker that knows how the password was generated, including what word list was used. Any real-world attacker will have to brute-force at least this many bits.