A prude is someone who is very easily shocked by sex, by bodies, or by “rude” talk — and the word is almost never kind. If you call a person a prude, you are saying they are too tight, too easily offended, maybe putting on a show of being more proper than they are. It can be used of a man or a woman, though for a long time it was thrown at women more often, which is part of why it can sting. You hear it in jokes, in arguments, and from older speakers; younger people may just say someone is “uptight.” It is about moral shock and display, not about being careful with money or danger. Though actually, the look-alike word prudent is a compliment, and this one is a poke.