Insult to Injury

Here's a tip: when you were put in charge of preparing a talk or lesson or whatever, and you spaced it, don't compound your sin and insult the audience by saying "um, you know, I was really busy and I didn't really have a chance to prepare much, so, just bear with me." Sorry, I will NOT bear with you. In fact, how dare you demand my indulgence after telling me you don't care enough to even prepare.