Not sure if it was a joke, but shouldn't a microwave oven shield the 2.4 GHz band pretty well?
Apparently modern wifi chips are just too good at picking up faint signals.
Also when a phone is in a microwave, the RF noise is also attenuated, so that helps a little (amplifier noise is unaffected).
But that's not even close to sufficient for actually isolating wireless transmissions. My microwave got 35-38 dB for WiFi signals when I measured it, and that got through a fairly reliable connection. You might want 90 dB or something like that if you want to ensure that you can't extract the data from the noise - so perhaps a starting point might be to put your device in a small microwave oven and put that oven in a large microwave oven :)
> I also tried putting my phone in a (turned off!) microwave, but this did not work either, it was still connected to the Wi-Fi access point.
But yeah I would have thought the same.
Never checked if true. But that could explain why they're so "leaky" at 2,4 Ghz (and other frequencies).