In the end, this is how the cookie crumbles.
Ladybug, fed up with the unending stream of puns, decides to beat Chat Noir at his own game. She starts small, a pun here and there, until months down the line she is reflexively punning everytime Chat speaks.
The cookie begins its crumble here, when they are facing an akumatized crazy cat lady. Chat, in an attempt to lighten the mood and draw attention to himslef, puns "Talk about /catty/" As was now the norm, Ladybug instinctively puns back "Spot on, Kitty."
The next day Chloe is in a terrible mood, apparently the crazy cat lady scarred her mentally. Adrien, fed up with her, whispers to himself a little too loudly "Talk about /catty/"
"Spot on, Ki-" Marinette reflexively speaks up, conditioned to respond to Chat Noirs voice and puns, only to freeze halfway through her retort, eyes wide.
Her face is frozen in an unattractive gape, skin turning as red as her alter egos costume. Adrien himself is no better off, face matching hers in color, with a shocked and ecstatic grin. Marinette recovers quickly, giving him Ladybug's trademarked I-am-not-amused face.
He gives a feline grin and nearly purrs "Well, looks like we will have to have a /Chat/ later." She gifts him with a nod, knowing that her best friend Alya would no doubt try to interrogate her before the day is over. Luckily for the two, the teacher walks in and calls the class to order, leaving the student with no chance or choice to chat.