1. A word is invented.
2. The word gets popular.
3. The word gets overused to death.
4. People don't like the word anymore.
5. A new word gets invented to take its place.
6. The new word gets popular.
7. The new word gets overused to death.
8. People don't like the new word anymore.
9. See part 5.
Ever wondered why we have so many euphemisms for "penis"?
Now you know.