Humor on the errors.
- No one is ever as funny as they think they are.
- Sure, humor can make the message more "interesting", but if you're sending an apology there's a chance that people are pissed off, and I'd like to minimize that chance of the fringe getting marginally more pissed because of an attempt at humor.
- There's opportunities aplenty to be funny when things are going well. When you screw up, being professional, efficientm and genuine just seems to be the smarter way to go.