Some people think Waluigi's name is dumb or makes no sense.
In Japanese, warui is a word meaning "bad or evil", and in Japanese, Luigi is pronouced like "Ruiji", so they combined them and you have "Waruiji", or Waluigi- hence a "bad Luigi".
Similarly, Wario's name was made the same way- crossing warui with Mario to get Wario, hence a "bad Mario".
Some people think Waluigi should have been called Î"uigi since he has a "Î"" symbol on his hat- it would have been pronounced like Guigi, or Gwuigi, or some people said it could have been used to rename him Î"ualuigi, which would be pronounced like Gualugi- but that symbol isn't a said letter.
If he had been called Î"uigi, would that have confused people?