The Coffee Conundrum

Every day at 3 PM, there’s this one customer, let's call him Mark, who orders the same drink every single time. He always acts so important in his tailored suits... And I’m tired of it. One day, I accidentally gave him decaf when he asked for espresso. I watched him struggle to stay awake through meetings later. Now I feel a bit guilty about it but also kinda satisfied. Am I the asshole? Is messing with someone's coffee just childish? What would you do?...