Full Throttle. The Ben's real last name is...

...Throttle!
I read about it in Wikipedia. Have a look:

In the game credits and manual the player's last name was listed as the main character "Whathisname". However later Tim Schafer admitted that the Ben's last name – “Throttle”. It was not announced because of the fear of legal action by the creators of the animated series "Biker Mice from Mars" (one of the characters which are also called “Throttle”).
Truly yours,
Alexander.
(С уважением,
Александр).