Let's not be recommending damaging their product though.
As a technician I can explain why to never put a phone in the fridge. Fridges have a higher humidity, and putting you phone inside will cause it to cool down, however it will also cause that colder more humid air to get traped inside the phone, this will condensate and can then cause corrosion inside the phone, which may break it entirely.
Inside the phone there is also a moisture sensor, that is coloured white, when the phone gets even slightly damp inside it turns pink, indicating water damage, this may also be triggered by the condensation from the fridge. This would void any warranty, and also will increase any outside of warranty repairs by Apple as they will insist on replacing the logic board as part of any repairs even if it isn't faulty.
The only benefit the fridge will have is to cool an over heating phone, but in that case it's far better to just let the phone cool down naturally for the above reasons.