ARE CURSES REAL?

No I’m not joking at all... I know this sounds stupid but I’m weirded out. I was at work today. And this young girl and her boyfriend came to the counter to buy candles. She couldn’t get her coupon to load, so I told her unfortunately I did not have any to give to her. She got really angry with me, and she actually TOLD ME. She was going to curse me for being rude and not helping someone out. She then stormed out.

Now I’ve never had someone say that to me. And not gonna lie...

I’m pretty freaked out. Are curses real?