If you think this job is going to be easy, you're in for a 'rude shock'. [=you will be unpleasantly shocked when you find out that this job is not easy at all]
He's about to have a 'rude awakening'. [=he's about to find out something that will shock him unpleasantly]
I was 'rudely' [=suddenly and unpleasantly] awakened from my nap.
(..) - By now he could be anywhere. - He won't come after me. - Oh, really? - He won't. I can't explain it. He would consider that rude. - It's over. She's dead. - It's not your fault it worked out like this. The thing is that Lecter said everything we need to catch him is in these pages. (..)1991 The Silence of the Lambs