In the third issues of Boom Kids' The Muppet Show Comic Book, collected in the trade The Muppet Show Comic Book: On The Road, Speedy Delivery Service drops off a very large, heavy package at the Muppet Theater, "Special Fright."
"Don'tcha mean special freight?" Pops asks, setting up the visual pun in the panel above. Does that particular rendition of that Frankenstein's monster look familiar? The appearance of his nose high above his eyeballs certainly calls to mind Dick Briefer's strikingly idiosyncratic version of the monster in his Frankenstein comics.
A second brief cameo of a Briefer-esque Frankenstein, this one even more closely resembling Briefer's monster, occurs in The Muppet Show Comic Book #11, which I previously reviewed here and which is collected in The Muppet Show Comic Book: Muppet Mash: