Ahem, to play Devil's advocate, I suffered a miscarriage last year (which happened whilst I was at the office) and only one person in my team [Colleague A] knew about it.
When I returned to work after a couple of days off, I realised that my being absent had meant a very important meeting which had taken months to set up with Colleague A had to be postponed as Colleague B who'd agreed to chair it on my behalf had not done so because she [in her words] could not be bothered to read the paperwork required.
When I got back to the [open plan] office, Colleague A and I were discussing the meeting and he asked me if I was actually supposed to be back so soon. I whispered to him that the doctor had said it was fine and apologised about the meeting having to be cancelled.
Colleagues B and C complained to my manager that, by whispering, I was having a private conversation in the office, it was "wrong" for me to do so and that, from what they had overheard, I had been having a dig at Colleague B (so I guess my whisper wasn't that much of a whisper - that, or they were deliberately eavesdropping).
Even after they found out what the background to that whisper was, they pursued it as a grievance and my manager [who resented the fact I'd been promoted to a deputy-type level to her] backed them up.
Suffice to say, I left that job exactly 28 days later. However, I'm pleased to say that whilst I went on to almost double my salary in my next post and move a rung up the career ladder, my manager and Colleague B were later fired for harassment and bullying (partly related to that incident).
Just so you know, not all whispers are designed to be childish or malicious ...