<iframe width="560" height="315" src="http://www.youtube.com/embed/8ssuHHRAdGI?rel=0" frameborder="0" allowfullscreen></iframe>
Sounds like he knew he was doing that and just did it for the laughs. Cause he started saying "wi-fi" properly and then switched at the last moment. My guess is that he said that the first time he ever saw the word and got corrected and now thinks it's funny to say. Not trying to ruin the humor, cause Chuck's words and pronunciation always make for good entertainment on it's own, but that's just the vibe I got from this.