Once I attended a wedding where the hosts had requested guests show up in costume. Most people showed up in costumes that clearly were just minimal effort - a mask, a cape, whatever. Some people showed up in really intense costumes. I don’t remember what my then-girlfriend and I wore but it was somewhere in the middle of the two.

When we got there, we encountered a mutual friend of the groom and me. He was in, simply, a suit, something one would wear to a more traditional wedding. We jokingly said “where’s your costume?”

He responded “I don’t wear costumes because I’m an adult.”