Is it illegal to sell marijuana or other drugs on facebook, why are people doing this?

[BIG D]

I'm a member of legalize marijuana facebook page, which is supposed to be an informative page about states that have legalized marijuana and things like that. Under the status of one of the posts there was a couple of comments from different people saying they have different strains of marijuana for sale. I have seen other people post on music artist's pages and stuff like that selling drugs. Here is what this person commented... We sell top quality medical marijuana at affordable prices.
Discrete delivery available in vacuum sealed containers to any location. Tracking numbers avaiable,contact now via (801) 692-7655) with your order or send me a Friend request with a message.
Some Available strains include;

***BLUEBERRY YUM YUM
***MANGO KUSH
***GIRL SCOUT
***GRAND DADDY PURPLE
***PURPLE HAZE AND MORE....

We also have ACTAVIS PROMETH WITH CODIENE PURPLE COUPH SYRUP, INJECTABLE STERIODS ,ANABOLIC STERIODS and many other strains not mentioned above!!!

The person's name is supposedly John Cooper. Where can you report this, or is this legal? Why are people so stupid to do this online where everyone can see. There was a different person right underneath that comment, who commented just about the same thing. It's probably spam or someone joking, but if it's real, isn't it illegal? Just go to the legalize marijuana facebook page and it was under a status posted 30 minutes ago if you have facebook and are interested.
@ siamesedharma.... Why would you report this question, I was just finding out who I can report this activity too, and why other people are so stupid to do this online?
I did not mean to post this person's details about what they were selling, but I just wanted to show everyone how they were selling this, and what I should do to report this.
@ bill... dude i was just showing some random persons post on that facebook page as evidence, of course im not stupid i was wondering why other people are stupid to do this. I should have just explained about the ad i saw and not post it. My bad.
@ siamese... I went to great lengths to show the random person's facebook comment and to find out what to do to report it. I am not stupid and would never do such a thing. I was wondering why others are stupid and showing why they would post this on the internet. It was totally un intentional, but now I see how it could be taken the wrong way. Yahoo would not let me delete it and reword my question once a question has been answered. I was just showing this random person's comment as evidence.

[siamesedharma]

Report it to Facebook, just like I am reporting your question to Yahoo.

I reported your question because you are advertising the sale of illegal drugs, and you even included a phone number. If you did not intend to do that, all you need to do is simply edit or delete the question. But it looks to me like you took quite a bit of effort to type all that information. I don't think you did it accidentally.

[BILL]

You say you are just asking if it's legal, but you post the ad including the phone number. Posting on Facebook and Yahoo may not be the smartest move since marijuana is still illegal under federal law.