The title of this lesson includes a word that you probably have never seen before. To put it simply, this word specifically describes words that have undergone internal inversion. How the word gets inverted may differ from others. In Japanese this is technically referred to as 倒語. Usually, though, it is referred to as 逆（さ）読み.
These sorts of readings have existed in Japanese for some time. The purpose of this inversion is to bring about some sort of emphasis. This sort of change is seen in various parts of any language regardless of one's generation. Though the use of these inversions is quite varied, they are generally treated as in-group lingo or 隠語. In Japanese 隠語 typically have negative stereotypes attached to them, and they will almost certainly only be known and used by a small group of people.
These sorts of words become most popular in Japan during the 江戸時代. Examples that were later passed down to the present day as the common word include しだらない (slovenly) → だらしない. Others that didn't quite catch on include words like キセル (tobacco pipe) → セルキ. Other examples like タネ (seed/subject matter) → ネタ ((joke) material/topping of nigirizushi) resulted into words with (slightly) different meanings.
These words got some publicity in the 1980s due to broadcast writers who previously wrote memos to publications (ハガキ職人) utilizing such expressions. A common example at the name was calling 六本木 ギロッポン.
It's also important to note that at an individual level, 逆さ読み come about naturally.
Below is a list of examples. Over time, notes of usage and example sentences will be added. Some of these words are r-rated words, but they are examples nonetheless of this phenomenon. Thus, they will be noted.
It's also important to note that 逆読み are often used in brand names. Some examples include the following.
|HAKUBI C||HAKUBI from 美白||バソキヤ||From 焼きそば||EZAK||From 風邪|
More Historic Examples
Sometimes some phrases read backwards make sense, but sometimes you get just another sentence. These are often made as brain teasers or jokes.