Another Alien Concept...
Upon reading all these “humans are weird” and “Earth is space Australia” posts, I had an idea.
Other social species on our planet typically join together to wash and clean each other in a group (apes picking bugs off of each other, cats grooming each other’s fur, etc.) But we humans tend to shower or bathe ourselves alone as soon as we are able to, and freak out when someone randomly comes into the room when we’re unclothed without warning.
Imagine aliens not having this sense of privacy, and they see each other unclothed all the time and are not bothered by it nor see it as an invasion of privacy. Imagine an alien walking into the quarters of their human co-officer and being bombarded by shouts of panic for them to get out and close the door, or they find the door to the washing room has been locked, or blocked, from the inside to prevent anyone else from coming in while the human is showering.