Tavern owner who's often prank-called by Bart Simpson

MOE

The grumpy bartender with a signature catchphrase in Springfield’s favorite watering hole.

This clue refers to Moe Szyslak, the grumpy bartender and owner of Moe's Tavern in The Simpsons. Bart Simpson frequently prank-calls Moe with fake names (like "Hugh Jass" or "Seymour Butts") as a running gag in the show. The answer is simply "MOE," the character's well-known nickname. If you're a fan of the series, this one’s a classic reference.