un-croissant
Explanation
The comic depicts a couple having sex in doggy-style position. The woman notices the man is doing something unusual behind her and asks, "What are you doing back there?" She discovers he is juggling, and he defends himself: "Juggling is how I stretch things out! It's how I last longer!"
She suggests he "just think about sports or whatever to last longer," but he insists: "It's doggy style! This is my private time back here and I am using it productively and well!"
The final panel escalates the absurdity: he starts practicing French on a language app, saying "Je voudrais un croissant." When she asks if he's doing his French language app, he defiantly responds: "This is my private time!"
The humor comes from the man treating the physical separation of doggy-style sex as if it grants him a private workspace, completely ignoring that he is still an active participant in an intimate act. The escalation from juggling to language learning heightens the absurdity. Weinersmith is playing with the idea of multitasking culture taken to its logical extreme - the man is so obsessed with productivity that even during sex he cannot resist optimizing his time. The title "un-croissant" references the French phrase he practices.