The color red makes people think of many things. One things that we associate red with in American English is with embarrassment and/or shame. Let me (Mark) tell you a story:
When I was a teenager, I was an exchange student in Bogota, Colombia. I was new to Spanish, and made all of the mistakes that language students typically make. Bad verb-subject combinations, mistaken vocabulary, and poor pronunciation were just some of the problems that I had when I was learning the language. In fact, when I work with my students that are prepping for their Cambridge ESOL Exams or TOEFL, I tell them that I made much worse mistakes than they could ever imagine.
One day, in a Spanish class at the school in Bogota, I was asked to answer questions from various students. They would ask me in English (giving them a chance to practice) and I would have to answer in Spanish (forcing me to practice as well). One person asked me about a time I had been embarrassed. I told them as best as I could about spilling a soda on my pants at a shopping mall, and said “Estaba embarazado.” After the teacher looked at me curiously several times (and after much laughter from the 40 or so students in the class), I was informed that I had told the entire class that I was pregnant.
How embarrassing. How biologically impossible.
My face turned red. I was blushing. I was very red-faced that day in class.