Intwesting. Is it due to lack of air-tightness, so that air seeps in while the door is closed mostly removing the pressure difference? Or is the force imparted just nudging the door open enough to let air rush in? (I never hear a whooossh when i open the fridge)

I think it is partially because air leaks in when the door is opened, but also because the fridge is not airtight in the first place. Another factor could be that usually the door is only open for a short time each time it is used, which means that much cold air remains inside. To this some more warm air is added to equalize the pressure, and when the door is closed this warm air cools - but now the fridge contains more moles of air than it would have if I had just filled it with warm air and let it cool.

Overall, it is fascinating how even everyday objects hide complex physics. Processor fan aerodynamics, paper wrinkling, bookshelf stability, shower curtain movements... you name it.

you are some sick people. Get help. Quick.