Jane: Tomorrow I'm going to go to the DMV to take my driving test... again! I've already failed twice!
Cindy: Good luck! I hope you pass. I'll keep my fingers crossed for you.
Paul: Hey John, you had a job interview last week, right? Have you heard back from them yet?
John: No, I haven't heard back from them yet. The interview went really well though. I really want that job. I'm keeping my fingers crossed.
Meaning: to keep your fingers crossed is used in different situations where you are wishing someone luck. This can be used when you are wishing good luck for yourself or for someone else. Don't forget that this idiom uses the plural "fingers," not the singluar "finger."
This idiom can be found in the LSI textbook Speaking Savvy. This book is used at LSI schools to teach Level 5 Speaking. For more information, please visit: www.languagesystems.com