One day this same friend invited me to a party . It was not a real party , it was some kind of informal get-together . Since it was summertime he had a cookout where most of his American friends and  s were known to me , but there were others I had never met before . It was the most embarrassing party for me when I noticed that everyone was wearing jeans and simple T-shirts for the day , while I arrived in proper dress with my shoes and my hair all fixed for a fancy party . It was hard to explain my embarrassment to the other guests . When one of them turned around and said "What nice clothes ! What's the occasion ?" I felt my face burning hot with embarrassment . I did not answer at all . Many times I thought about going home and changing , but I knew that they would notice . It would be even worse for me , because I knew they would quickly think that I felt out of place . So I wanted to pretend that I was okay . People often wear  _    for an informal party according to the passage.
. a tie a T-shirt a dress a hat