know (something) forward(s) and backward(s)
know (something) forward(s) and backward(s)
To be extremely familiar with a particular subject, field, or piece of media. Primarily heard in US. I've read this book so many times, I know it forwards and backwards. Samantha knows engines forward and backward, so you should ask her about the trouble you're having with your car.
Farlex Dictionary of Idioms. © 2015 Farlex, Inc, all rights reserved.
know something backwards and forwards and know something forwards and backwards
Fig. to know something very well; to know a passage of language so well that one could recite it backwards as well as forwards. Of course I've memorized my speech. I know it backwards and forwards.
McGraw-Hill Dictionary of American Idioms and Phrasal Verbs. © 2002 by The McGraw-Hill Companies, Inc.