don’t have a cow, man 

1) A saying said by Bart Simpson in seasons 1-9 of the popular animated comedy The Simpsons, until someone got themselves fired and everything got screwed up.

Nelson: You’re stupid! Haw Haw!
Bart: Don’t have a cow, man!

don’t have a cow, man by Bluebird42 March 4, 2018

Don’t have a cow, man! 

An admonition spoken to a male seahorse who is concerned that he's gonna give birth to sea CATTLE instead of sea HORSES.

Most creatures reproduce though the female, with the male providing fertilization of her eggs while their still "in her oven". But male seahorses do somewhat the opposite --- the female deposits her sterile eggs into the male's sperm-filled egg-pouch, where the eggs are fertilized and remain till they hatch. Once in a while, though, something goes wrong with the process, and the male becomes concerned that his eggs are turning into aquatic cattle instead of horses, prompting others in his clan to anxiously admonish, "Don’t have a cow, man!"

Don’t have a cow, man! by QuacksO May 14, 2018

Don't have a cow man 

One of Bart Simpson's telltale catchphrases

"don't have a cow man" said Bart after he burnt down Skinner's house

Don't have a cow man by B. B. Turtle-Blackbee October 8, 2020