This is the 7874th most frequent Russian word.
карелсон
"Карелсон" is likely a misspelling or variation of "Карлсон," referring to "Karlsson," a playful fictional character from Swedish author Astrid Lindgren's books, popular in Russian culture.
This usage refers to the name of the fictional character from Astrid Lindgren's books, representing a proper noun here.
Карлсон живет на крыше.
Carlson lives on the roof.
Here, 'Карелсон' is used as symbolic language to metaphorically reference someone acting carefree or indulgently, drawing from the characteristics of the fictional character.
Ты ведешь себя как Карлсон, который прилетел поесть варенье.
You behave like Carlson who flew in to eat jam.
In this sentence, 'Карелсон' appears as a title element referring to a beloved piece of literature for children.