The following examples from Amharic (Afro-Asiatic) illustrate a form of language disguise or play language (like Pig Latin) used by young women in the Ethiopian capital, Addis Ababa (McCarthy 1984: 306):
$$\begin{array}{lll}\text { g"aro } & \text { 'backyard' g"gyrar } \\\text { gin } & \text { but' } & \text { gaynen } \\\text { matta } &\text{'come' } & \text { mayt'at } \\\text { kfu } & \text { 'cruel' } & \text { kayfof } \\\text { hed } & \text { 'go' } & \text {hayded}\\\text{man } & \text { 'who' } & \text { maynen }\end{array}$$
Figure out the morphological rule that creates the play language version (the third column) of the Amharic words. What kind of morphological rule is this?