A herd of cows is what one calls a large grouping of cows.

Frequently, the pun of "herd" and "heard" has been used by the Muppets in several productions, mainly pertaining to cows, but also referring to other groupings of animals as well. The typical exchange is as follows:

“ [Character refers to a bunch of cows] Not a bunch, herd. Heard of what? Herd of cows. Of course I've heard of cows. No, the cow's herd. I don't care what the cow heard!”

The joke was used by Abbott and Costello as early as 1953.

Uses of joke

The joke is used as the centerpiece of the Veterinarian's Hospital sketch in episode 211 of The Muppet Show.

The joke is used in Sing-Along, Dance-Along, Do-Along following the elephant song.

In a Global Grover segment, Grover and Fred the Wonder Horse watch a film about cow herding. Following the film, Grover asks Fred if he's ever herd a cow before. They hear a nearby moo and Fred replies, "I heard one now."

Upon hearing Elmo and Abby Cadabby mooing like cows in Episode 4157, Gladys the Cow arrives saying, "Methinks I heard a herd of cows".

The Muppets episode "Walk the Swine" has Fozzie trying to set up the joke (using a "heard of buffalo") to an unreceptive audience.

In Episode 4603 of Sesame Street, safari tour leader Grover says he, Elmo and a monkey passenger can pretend to be a herd of elephants. "Of course Elmo's heard of elephants," Elmo replies.