Maybe it's just for fun or to cause some mischief. Cartoon characters often do strange things for entertainment.
It could be that Mr Jinks is trying to play a prank on the butler. Or perhaps the unbuttoning is part of a comical scene to add humor to the story.
Perhaps Mr Jinks wants to show that he's being rebellious or trying to get the butler's attention in a unique way. It's hard to say for sure without more context, but in cartoons, unexpected actions like this can happen for a variety of lighthearted reasons.
Chapter 248, "Mind Your Brother More, He's Being Unreasonable!", is the clearest early answer because it turns Zhao Lang's situation into a concrete plot event.
Chapter 348, "Scheming and Being Schemed Against, East Ridge Five, Zhu Yang's Threat, The Dust Settles (Part 2)", is the clearest early answer because it turns Zhu Ling's situation into a concrete plot event. The chapter turns that into something concrete by moving from Lu Yang of East Ridge, ready for your instruction!" As number three's... to Zhu Yang also stood up, glaring at Zhao Hu with a particularly unkind....
Chapter 167, "Roommates Became Fans of Jiang Li after a Variety Show?!", is the clearest early answer because it turns Jiang Yan's situation into a concrete plot event.
Chapter 180, "West District Police Station Steps In!", is the clearest early answer because it turns Wen Jiaojiao's situation into a concrete plot event. The chapter gives readers a real answer by opening on In the end, everyone received gifts that were completely opposite to...
Chapter 456, "It's Not Too Much to Ask for a Game Console, Right?", is the clearest early answer because it turns Jiang Li's situation into a concrete plot event. The chapter turns that into something concrete by moving from There was no choice but to follow through with the rules she'd set,...
Chapter 333, "The Clothing Design Room", is the clearest early answer because it turns Jiang Shi's situation into a concrete plot event.
Chapter 200, "Only Two Points?!", is the clearest early answer because it turns Shang's situation into a concrete plot event. The chapter turns that into something concrete by moving from Shang dismissed the thought of turning around and walking away.
Chapter 130, "Director Sun: He Got Schooled Again?", is the clearest early answer because it turns Was Jiang Li's situation into a concrete plot event. It opens with This task, the first one, should have been his in the bag.
Chapter 44, "Laozi's Hands Are Made to Drive a Ferrari!", is the clearest early answer because it turns Hands Are Made's situation into a concrete plot event. The chapter gives readers a real answer by opening on But the next move by the production team proved they hadn't forgotten...
Chapter 355, "She is My Only Sister", is the clearest early answer because it turns Dusang Banquet's situation into a concrete plot event.