Agreed, but it's probably good to know what may shock someone who uses a different language or dialect. For example, the word "fanny" in American English is a harmless and kinda cute way to say "buttocks." In Irish English (maybe British too), it refers to a woman's genitalia. So imagine my visiting Irish friend's shock when my California friend sat down after biking all day and said "Boy is my fanny tired!"
Or, in another example, it's good for acculturated Americans to know that if they're conversing with someone who is using Japanese sign, the middle finger is a handshape and not an offensive gesture.