This effect can occur when programming a computer. In computer languages, words like 'while', 'next', 'last', or 'else' take on new meanings which only make sense in the context of the computer language. As well, the laws of English grammar and punctuation do not apply, so these words don't appear in sentences as we expect to see them.
The result of all of this occured to me whilst I was debugging a fairly hairy while-loop in Perl. I was reading code like "while ($x) { $y or last; $z++ and next; ..." and saying it out loud to myself. All of a sudden I lost all sense of the meaning of the word 'last'. I produced the sound experimentally with my mouth and decided it was very odd. "Last... last... last..." Very nasal and alien to me. I then tried 'next' and found the same strangeness. The episode was extremely creepy but the feeling went away when I stopped working and took a break.