Professor Fleece

Professor Fleece is a yodeling instructor who visits The Furchester Hotel in the episode "Yodel-Ay-Hee-Hoo!," he's come to town to attend a yodeling convention along with 27 other guests.

He teaches the Furchesters, Elmo, and Cookie Monster how to yodel as a means of communication when their phones stop working, and their back up phone system (cans with string attached to them) prove ineffective.