II Kings 2:23-24

"Then he went up from there to Bethel; and as he was going up the road, some youths came from the city and mocked him, and said to him, 'Go up, you baldhead! Go up, you baldhead!'"

"So he turned around and looked at them, and pronounced a curse on them in the name of the Lord. And two female bears came out of the woods and mauled forty-two of the youths."

(They weren't just insulting him casually. Because Elijah was so hairy, Elisha seemed hairless in comparison. A crowd of youth came and mocked him. This was just like mocking the Lord Himself. That's why the judgment was so hefty on them.)