This rejected New Yorker comic comes from The Best of the Rejection Collection: 293 Cartoons That Were Too Dumb, Too Dark, or Too Naughty for The New Yorker, and was created by Harry Bliss. It would’ve been one of their most-recirculated had it been approved — maybe even bigger than this one.
If you don’t get the joke, ask anyone who has a dog. And in case you were wondering, the proper response for such a question — unless you’ve got some really relaxed boundaries (and hey, more power to you) — is “I’m your friend, but I’m not that friend.”
Thanks to Inside Hook for the find!