Help!

[lollardfish]

There's a Doonesbury comic from years ago (15 or more) where the history teacher loses it and starts to shout patent nonsense, "Black is white" is the one I remember, but could also be up is down, day is night, whatever. And the students diligently take notes, "Gee, I didn't know half of this stuff!"

I need a copy of it, pronto. Help!

Edit: Got it, thanks!