[NotOscarWilde]

I like this anecdote because it contains a non-sexist but inappropriate statement. It also shows that there are at least two possible mindsets:

* I talk to my coworkers like they are my mother

and your colleague's

* I talk to my coworkers like they are my friends

The fact that the statement was non-sexist hints at the problem being the second mindset; as for me, I make sure not to say sexist (and racist and so on) things to anyone but I am okay with talking about sex and other personal-jovial matters with my actual friends.

The "mother" analogy still has some flaws, though -- for instance, you can talk to your mother about financial, health-related and personal troubles, whereas your coworkers will feel uneasy with such information. Another thing is politics -- I try to politely argue against my mother's political views (say anti-immigration), but I think doing so in the workplace is a very bad idea.

[pdex]

I think you get most of it, I was trying to convey that if you say something to colleagues at the workplace that is too disrespectful, sexually suggestive, vulgar or sexist to mention in front of either of your parents, it's a good common sense "warning flag" that it's probably not safe for work. I struggle with this myself, having a dark sense of humor. I hate seeing the perfect set up for a raunchy/sick punchline going to waste, but I'd also like to keep my job :)

Politics is a bit of a gray area. It's very easy to make people uncomfortable without realizing it, it's just a shitstorm waiting to happen. I try to avoid it unless I'm speaking in private with a colleague who I know extremely well.

[Grishnakh]

The "like they are my mother" thing is really a bad analogy. A better one would be: "talk to coworkers like they are your grandmother" or "your aunt you only see once a year" or "your mother's female friend from church".