Yes, it's an idiom which means 'have a secret idea or plan that you intend to use later' or 'have a surprise plan or solution (to a problem)'.
You may have something good or bad in your sleeve, for example, you may try to cheat by having a card hidden in your sleeve:) I hope you have something great for a puzzling problem or a situation, though.
You could write a short paragraph by using the idiom - it can be fun if you really get the picture. Here's a sample paragraph for you:
I'm waiting for Expector's monthly blog challenge. It's time for him to come up with one or he should have published one for us to write a challenge blog, but somehow he's failed to do so this month. He may have something up his sleeve - are you ready for a surprise?
So, you see, you don't need to write something lengthy - a short paragraph will do. Don't forget to add the 'correction' tag if you really want to be corrected in public - some people may feel so embarrassed or even offended when they're corrected.
Your turn...
'get the picture' = 'understand something'
Comments
Great! I'll check them out now! Keep it up!
Hello Sir, this is my piece of work
http://www.myenglishclub.com/profiles/blogs/blong-challenge-have-so...
http://www.myenglishclub.com/profiles/blogs/expector-s-challenge-ha...
Hi Seeker,
Thanks for taking part in the challenge. I'll check your blog out soon.
Hi Adaline,
Great! I'll check it out right now.
Hi Danny,
Thanks for the comment! You're welcome to join - feel free to correct us, especially when you see the 'correction' tag, which means they'd appreciate it if you help correct them.
Dear Expector, Thank you for the lovely challenge. I never heard about this idiom before. I learned it today and try to write some thing. Please correct it for me. Thank you. I appreciate it.
http://www.myenglishclub.com/profiles/blogs/expector-s-blog-challen...
Dear Expector! It is a great challenge! And your example related to cards is very right. I would never think up anything better. Playing cards, especially pocker, we always tell a winner "Have you had a joker or a few aces in your sleeve?" If learners like, I will help you correct their mistakes. Thank you!
@mitran
Thanks!
@Barbare
Great! I'll check it out immediately.
hihihi..still thinking my dear Teacher...