On a tip from Boing Boing reader JayHavvic, I checked out this 1924 recording of Will Rogers keynoting at an annual bankers' convention, giving them the gears with as much gusto as, say, Colbert gave GW Bush. It's a must-listen.
The audio comes from 78Records, an excellent site with serious bandwidth problems. So I've uploaded a copy to the Internet Archive for easier downloading.
MP3: Will Rogers Talks to the Bankers, VICTOR_45374-A (1924)
(Thanks, JayHavvic!)