We have all done things like this. I like to tell stories with some help at the end. So here is another one.
I sold my very large utility trailer, but chose to put the old tires back on since they were still good and use the new tires for something else. After a period I had not used the tires and decided to just give the tires away. I even offered to deliver them. I e-mailed using the @company e-mail list which was created to reach only the employees within our local corporate office. However, early that morning just before I arrived to type the e-mail, the @company e-mail list was changed to e-mail the entire company globally.
Soon I started receiving e-mails from places like Australia. Ooopppsss!
I have a sense of humor so I simply e-mailed back that I would need a couch to crash on when I get there.
And that is the point. We all goof-up from time to time. The key is to see the humor in life and use it to defuse the embarrassment somewhat. Sure it is embarrassing. Okay. So what? In your case, what is a kettle worth? Nothing really. Offer to replace it. Odds are, no one will take your money. You can offer bitcoins and ask for change back for example. Start at the top. Sure the department head maybe should not have said anything at all. It may be that they like you and just wanted to give you some jazz. Be that as it may, start there. Perhaps you needed a nap and nothing puts you to sleep faster than warm milk. Maybe even with Brandy. Maybe the department head will sing a lullaby to help. You can only ask.
Find the humor, use it, and all will be okay. Certainly they are not going to fire you. If they did, I would go to the unemployment office and give the reason that you simply wanted to warm your milk and being coffee drinkers they got upset that you were not hardcore enough. See where I am going?
This not enough to get upset about. Really. Would I lie to you?