Program performed illegal operation. Let's call the police
One of our Colleague's young kids were working on a computer when it popped up a message "Program has performed illegal operation and will be shut down". He got urgent call from his 9 year old daughter "Dad, does this mean that the police will come?".
So next time you ignore a UX guideline think thrice.
And yes this is a true story and I didn't cook it up.