For some reasons I will be using CC BY NC SA license thorough out my project/program, and I know that this license is not approved by OSI or FSF because it have NC ( i.e. non-commercial) clause in it. So what if I use this license anyway in my project, will I get sued for doing so?
I don't think that you will get sued, but the Creative Commons FAQ "recommend[s] against using Creative Commons licenses for software."
The FAQ goes on to say,
Instead, we strongly encourage you to use one of the very good software licenses which are already available. We recommend considering licenses made available by the Free Software Foundation or listed as “open source” by the Open Source Initiative.
The reasons for this are related to the concept of source code, patent rights and incompatibility with major open-source licences (my emphasis):
Unlike software-specific licenses, CC licenses do not contain specific terms about the distribution of source code, which is often important to ensuring the free reuse and modifiability of software. Many software licenses also address patent rights, which are important to software but may not be applicable to other copyrightable works. Additionally, our licenses are currently not compatible with the major software licenses, so it would be difficult to integrate CC-licensed work with other free software. Existing software licenses were designed specifically for use with software and offer a similar set of rights to the Creative Commons licenses.
Creative Commons BY-SA 4.0 is compatible with GPL version 3, and CC0 Public Domain Dedication is compatible with GPL, so you can use that for software if you want.
Of course, you can use Creative Commons for docs, manuals, tutorials, artwork etc. related to the software.
Updated in response to Zeeshan Shaikh's comment, "can you name few software licenses which have similar set of rights to CC BY NC SA License please".
The NC (NonCommercial) variants of the Creative Commons licences prohibit reuse that is primarily commercial. As the Creative Commons FAQ points out,
CC's definition does not turn on the type of user: if you are a nonprofit or charitable organization, your use of an NC-licensed work could still run afoul of the NC restriction, and if you are a for-profit entity, your use of an NC-licensed work does not necessarily mean you have violated the term. Whether a use is commercial will depend on the specifics of the situation and the intentions of the user.
However, Clause 6 of OSI's open-source definition says,
The license must not restrict anyone from making use of the program in a specific field of endeavor. For example, it may not restrict the program from being used in a business, or from being used for genetic research.
This means that an OSI-approved licence must not prohibit commercial use of the software; this obviously includes using it for purposes that are primarily commercial. As far as I can see, NC condition in CC-NC-based licences conflicts with OSI open source definition.
Note also that freedom 0 in Richard Stallman's four freedoms says
The freedom to run the program as you wish, for any purpose (freedom 0).
This implies that commercial use is allowed. In addition, the phrase "as you wish" implies that the user does not need to inform you about how they use the software or needs to request your permission for certain ways of using the software.
With regard to Creative Commons' "BY" (Attribution) clause: many free software / open-source licences require that you retain the copyright of the "licensor" or creator, e.g. the Apache License, Version 2.0, the 3-Clause BSD License (see its first clause), GNU General Public License version 3, the MIT License, the Mozilla Public License 2.0 (see clause 3.4) or the less-well-known European Union Publice License, version 1.2 (see clause 5).
If the project is all your own work, or any contributors have clearly agreed that their contributions are also licensed under CC BY-NC-SA, then I don't see any major problem. There certainly aren't any grounds for being sued merely over that choice of licence.
My calculator runs code which is the work of a proper company, and is licensed under CC BY-NC-SA. The biggest problem is that such a restrictive licence is a big turn-off for some potential contributors. You can read a long thread on the licence choice wherein you can see that some people feel really strongly that they won't contribute to a non-free project (the thread dates back to an earlier time when the code was CC BY-NC-ND-SA, before the company agreed to relax the licence slightly, but the points made then still apply).
So your big problems with that licence are that it can be turn-off for contributors and the wider community, that it's not very well suited to software (a problem with all the CC licences, excepting CC0), and that it's non-free so you have to be very careful that no contributor accidentally puts eg GPL'ed code into it. Being sued over your choice of licence isn't likely to be a big problem.