How do you say you look pretty in Thai?

To say "you look pretty" in Thai, you would say "คุณดูสวย" (pronounced "khun doo suay"). Here, "คุณ" (khun) means "you," "ดู" (doo) means "look," and "สวย" (suay) means "pretty." This phrase can be used to compliment someone's appearance in a polite manner.