Okaaay, back to passive aggression...
I've been observing my PA colleague today, and I recognise the laugh!
She constantly tells callers on the phone that she can't possibly help them now as she's 'in the middle of something else' ha ha ha ha. Then keeps them holding on for a good few minutes.
How is this relevant or interesting to the caller? Just tell them you're busy right now but you'll call them back instead of trying to make them feel guilty for interrupting you ffs.