Idiom of the day - Catch (someone) off guard Meaning: To surprise someone by doing or saying something they did not expect. Example: I was caught off guard when Nicole came to my house without an invitation. If you'd like to practice using this idiom, please write back to me on this post with an example and I'll tell you if you're using it correctly :D Finally, if you're looking for a friendly and patient teacher please check out my profile. I look forward to meeting you. Thank you, Rianne :)