People get comfortable, relax their boundaries and behave like children.
Kids who are well behaved outside of the home are just as naughty at home as any others. It's because they feel safe, and for kids that's ok.
Every work place has variations on the issues you describe, depending on the personalities of staff and how management deal with them.
In my experience, the places that have the least drama are where the management are most skilled at dealing with people. Which sounds obvious but there's a great deal of management who don't know how to get staff to work effectively, let alone get on with each other.
Even for non management, there's a lot to discover about this stuff in the book The Five Dysfunctions of a Team by Patrick Lencioni.
Wednesdays are in the middle, so after lunchtime you are past half way through the week. Woohoo!
Mondays always fly by, I barely notice them.
Thursdays are when the excitement for the weekend starts to build, maybe even go for a pre-weekender.
But every week it's there, full of important work stuff and fully aware of making the week unnecessarily long and painful.
Tuesday.
It even sounds like it's giving you other options but it isn't, it's forcing dull bleakness onto everyone. You can't even enjoy a Tuesday night because you tried to put off Tuesday with Monday night. Can't do that again, at least until Thursday.
Fucking Tuesday, no matter how much gets done and how well, there's no joy in it. Just a numb acknowledgement that the time was passed as quickly as possible so we can get closer to Wednesday lunchtime.
Can't wait for Friday, seeing old friends. Good stuff happening at work on Wednesday and Thursday.
Fuck you Tuesday.