I'm glad my assistant finds my indifferent attitude funny, lol

I just had a phone call at work with an employee giving me attitude over a piece of mail they need delivered today, all making themselves out like their department is the most important (one of the fucking restaurants... really?) I'm already over these jackanapes today, so I told this person straight up "Lots of other people are getting mail right now and I don't have time for this bullshit." Bryanna looked over at me with eyes-widened and just started holding back her laughter. When I got off the phone, she was still cracking up, telling me I'm savage. I told her if she works here as long as I have, she'll be just like me and just stop giving a damn and start snapping back. What are they gonna do, report you for unprofessionalism when they were acting as such first?