Mario and Luigi doesn't have a last name

This is already known a long time ago
 
Thanks alot for pointing the obvious, Captain Obvious.
 
You know, that's weird because I went to the Wii U experience and there they said Luigi's last name was Mario. (I still think they don't have a last name anyways)
 
I'm actually fairly positive that it's impossible to not have a last name
 
Charles Martinet disagrees:

http://www.youtube.com/watch?v=AAjhjLuWbC8

(I'd link to the specific time the name come up, but I'm posting from work and the computer's not running YouTube properly - i.e. there's no sound).
 
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