So i am quite hesitate to tell people that i am doing a PhD. Majority of people who i know are expecting that i should know everything like a live wikipedia and my behaviour should be perfect. My employer also makes a joke (or not) that "you are a PhD, you should do something that my company can grow bigger" even though i work for only 2 days/week. Some of my friends are also making fun when i use swear words.

How do i deal with these?

Thanks

Try not to let it bother you and laugh it off, would be my advice. Don't tell everyone if you are worried. I often said 'completing a study' and people assumed I was doing a Masters or just didn't know enough to ask any more anyway.

Many or most people outside the world of PhDs and academia really don't understand what they are or what they involve and there are many myths about doctoral studies and doctorates. Your colleagues are probably just teasing rather than bullying and a lot of it would be 'tongue in cheek', eg-not meant personally but as a light joke. The other end of things is when people believe your PhD means that you are someone with your head 'in the clouds', who has no understanding of the practical or professional world. This myth is common for those of us who complete a PhD but continue to work in a form of professional work such as teaching (schools) or similar. It can also be common in Australia where advanced education can be perceived as elitist, which is not always celebrated in our strongly 'egalitarian' country (beyond the academy or the science lab).

What is more important is what you believe and the genuine support you get from friends or families who love you and support your growth and achievement (even if they don't always understand it very well).

When I tell people I'm ding a PhD most people assume I'm doing a course and going to lectures and stuff. I've got bored of trying to explain what a PhD actually is. That said, it doesn't bother me... I mean, unless someone works in academia, why would they necessarily know anything about postgraduate courses? I've not come across anyone making fun of me though. Well apart from my other half who refers to my working from home as "having the day off", but I think that's just because he knows it annoys me!

Well the best way to deal with it is humility, humour and a modicum of self-deprecation!

I am confused. What is there to deal with? The comments are clearly offered in jest and not intended to offend. Why on earth would you then not accept them in good faith without getting upset and offended?
I have never understood why people take offence at utterly trivial things. It really is a miserable way to live.
Lighten up a bit and maybe start thinking about how to respond in a teasing manner.
For example. Your boss wants you to do something to make his company grow? Tell him your idea for that is to sack him and hire a competent manager. You might want to smile when you say that in case he has no sense of humour either.

Well, I already know everything. Next question?