I suspect being a teacher is a bit different than public speaking. For one thing, you're talking to kids (or at least people who are presumably younger than you), and for another you're talking to the same people over and over again, so I'd guess that you'd eventually become comfortable with them. It's not exactly a room full of strangers.

You can blather on about scientific nonsense to me any time you want. Maybe if McKay were Welsh, I'd hear more than, "Blah blah blah, I'm a genius, yakkity yakkity, seriously intelligent, blah blah BLOW UP A PLANET!!?" when he talks.

Probably not though.