I happen to think that the training day episode of the British "The Office" is the funniest television moment ever. But before that, for a long time (and the current #2) my favorite was the 'Turkey Drop' episode of WKRP in Cincinnati. Absolutely hilarious.
If you haven't seen it, go find a copy of the whole episode. Here's a 30 second mashup.
Have a great thanksgiving and don't forget what the holiday is for. Praise the Lord.