It is rude to wear shoes in someone's house.
Ethan has just arrived at a friends house, who just got new carpet, and is knocking on the front door.
Ethan wants to go inside and hang out with his friend.
Ethan notices the shoes near the front door when his friend opens it and makes sure to remove his shoes before walking on the new carpet.
Ethan walks right in when his friend opens the door walking with his shoes on the new carpet.
Ethan's friend is happy to have his friend over to show off the new carpet and Ethan has fun visiting.
Ethan's friends freaks out that Ethan has shoes on the new carpet and gets mad at Ethan which is embarrassing for Ethan.