Example:

"...and then he said, 'Those weren't french toast sticks, those were two-year-old fish sticks!'"

Or:

"...and evidently the Secret Service isn't too fond of practical jokes."

Or the classic:

"...how was I supposed to know he was a guy? He was wearing a scarf and everything!"

Best followed by:

"Well his pants were off for ten minutes before you noticed, everyone at the party thought you were just playing along"

...I'd never been to Belize.

If that wasn't your sister, then who was it?

*look at elevator inspection sticker*

You: Uh oh.
Stranger: What? What is it?
You: Um, it's probably nothing.
Stranger: No really what?
You: Well...it's just that...I used to work for the place that makes this model of elevator.
Stranger: And?
You: *laughs nervously* Oh, it's probably nothing. It's just that some of the models were shipped out before we could do a full inspection of the parts and....I'm sure it's fine. Really.