Just some ideas to consider; no judgment on my part:

Best thing to keep in mind about people who are unkind to us is that changing ourselves to suit those people is highly unlikely to elicit a positive result, if you think that they are ill-intended towards you in the first place. Also, there is likely not a single soul walking this earth who is liked by every person they encounter, and if we spend time worrying about the people that don't like us we will be worrying until the end of time.

Regarding in the workplace though, it might be worth refining people's perception of you as being a jokester since that could work against their ability to see you as serious about the job, regardless of whether it's true or not. However, rather than attempt an entire personality change, which I don't even recommend as there can be loss of identity in taking such a thing on, and as you suggest can come off as fake to people -- why not just be more precise in your efforts? Don't share all the jokes all the time, but try cutting down a bit, saving the inclination to share them until moments present themselves in which you think folks can especially use the break of hearing one. In this way you can also be telling only your best ones! As well as showing greater capacity for discipline, which can translate well in the workplace, suggesting an ability to exert discipline in other areas as well.

Regarding your co-worker "Facebook friend", there's really not much reason I can think of to stay friends with someone who humiliates you on Facebook or in real life, but as another option, you could leave him in your friend list but just make it so that he can't see your posts. I don't remember how anymore as I hardly use the application, but it's never hard to find current information online. I haven't reviewed this but just as an example here's a youtube video from August of this year that explains how to do it.

Best wishes and good luck.