How do you know your attending is wrong? I mean, the moment you bust out something from First Aid/Blueprints/High Yield, they will THROW YOU DOWN with "After proving blah blah in multi-center, international, perfect clinical trial, I proposed it to XYZ National Academy and they notified me by EMAIL at 7:59 am before rounding that it was JUST approved." So... SHOW UP, SHUT UP, and LOOK IT UP.
But what I usually do (not because I'm trying to correct the guy, but instead because I'm a dumb ass) is ASK a question like, "What's your opinion about using a XYZ in this patient?" or "So do you usually do ABC in a patient like this?" I always couch my questions with "in a patient like this" because NOW you're deferring to their clinical experience/wisdom and not some crap that could be read out of a book... because if it can be, they will tell you to look it up AND give a presentation, putting a damper into your happy hour/work out time.
Also, don't forget what service you're on and who you're talking to. YOU have the benefit of rotating through different specialties every month... your attending doesn't. So DO NOT get into a long protracted discussion about the latest heart failure management or some crazy ass rheumatologic syndrome when you're on ortho or psych. I mean, seriously. Your attending will throw you down and make you do a presentation right after rounds. And your classmates and residents will just laugh at you. Remember, your attending has malpractice insurance... but you don't have I-just-got-clowned insurance.