The Office Prank Gone Wrong

I work in a small office with five others, all around my age. We're all friends and enjoy joking around to keep things light during long hours of paperwork. One day, I found out that our boss had developed an obsession for a new brand of fancy coffee that he would sip at his desk every morning. It's quite expensive, and the thought of him drinking it got me thinking. I decided to play a prank on him by substituting his coffee with just hot water mixed with chocolate syrup and some sugar, basically creating an instant, poor man’s version of his fancy stuff. I figured since he never saw where he put his coffee in the morning, this wouldn't be too obvious. But that's not what happened at all. The next day, my boss arrived early like usual but didn't touch the drink on his desk. After a few minutes of staring blankly into space while holding it, he finally looked up and asked if anyone had moved his coffee without telling him. Nobody admitted to it because none of us thought someone would actually tamper with his stuff. A week went by, and my boss didn’t stop asking if we knew anything about what was going on with his beloved drink. It got awkward, especially when he finally found out that all the coffee packets had been empty, meaning no one could've taken them to refill elsewhere. At some point, it dawned on me that I might be responsible since the prank never came up in our group's joking. So there I was, trying to figure out how to confess without looking too guilty or outright admitting that I’d played a trick on him just because of his expensive tastes. The whole thing is making us all look petty and childish in contrast to my boss’s patience waiting for an explanation from us. It’s embarrassing, but honestly, it's also hilarious when you see it objectively.