Why would someone post a comment with curse words on Facebook?

[SeeInElle]

I have a Facebook page and today happens to be my birthday. I have family members and colleagues on my Facebook page. Never have I posted anything crude or any curse words on my page. Then someone, today, that I have known for years (and who is about 20 years old than I am) posted on my page about "Happy Birthday B***h" and continued on for about a paragraph using other four letter words. When I saw this post, I deleted it and emailed them simply saying that I had people on my Facebook page that might take offense to the language she used. I honestly think this is a bit trashy. On her page she constantly makes lewd and crude posts. This is an educated and smart woman. I can understand using cruse words around your friends or if something is supposed to be humorous online (like on here occasionally) but I wouldn't go up to my parents or go to work and start talking about sh** or calling people b***h.
If I had a long history of posting these kinds of things on my Facebook I would understand or if I somehow gave off the impression that I thought this was ok to do in professional life (like if I was a rapper ect) but I just seriously do not understand how someone thinks this is appropriate behavior.
Does anyone have any insight?
This person I know was not hacked, and this was a woman not a man. I don't really understand the answer from Bahrath.

[Lucy Glass]

To be honest it is possible she could of been hacked

[Natalie]

If she's used the language in the past it's safe to assume she is aware of her language choices and any possible negative consequences that have come out of it. The only insight I can provide is that her diction is her personal choice and you did the right thing alerting her to the fact it made you uncomfortable. Her language could be a product of how she was raised or simply her decision in how she wishes to portray herself to you and others on social media.

[Bharath]

Ohh sister your are such a sweet one
dont care about those guys they are like dogs and always bark loud !
Dont care about it if we start feeling sad, if you are hurted etc etc ....
The one who commented will be happy because his intention is to hurt you , and his job is done perfectly!

In reverse if you are not sad,and if you are happy like before and have a smile on your face then he will think even '' even im trying to hurt her she is not hurted !! Then he gets hurted thinking about it !

And feel guilty some other time !
It works try my sweet sister !!!

[Erin]

She sounds like an unhappy person. Don't stress over how other people live their lives. You have let her know that it's not ok to cuss on your page and that's all that's needed.