The concept of word-shifts was introduced in Dmitri Borgmann's Language on Vacation (1965). Consider the word COLD for instance. Shifting each of the letters three spaces forward in the alphabet, COLD becomes FROG: and shifting the letters of CHEER seven spaces forward produces JOLLY. Dmitri offered many other examples in his book.
Word Ways: Vol. 35
, Article 22.
Available at: http://digitalcommons.butler.edu/wordways/vol35/iss4/22