Not a friend's kitchen, but My mom thinks it's weird that my husband and I use a sharpie to date everything that goes in the fridge pretty much. The expiration/best buy date is affected by when it was opened but it also helps us realize when something has been in there longer than we realize and should either be used up or thrown out.
Shredded cheese? Gets an opened date written. Lunch meat? Yep.
Shredded cheese? Gets an opened date written. Lunch meat? Yep.