I'm going to mess around at work
What makes you want to mess around when you're at work?
I need the money and I'm not getting anywhere with my business ideas.
I can understand your career frustrations, but it is wrong when you take the company's money and not do the job you were hired to do. You should focus on getting your job done first and foremost, otherwise you might get caught slacking off and be fired.
Nah, I'm going to show you that I can mess around at work and also I'm going to call you a sellout.
If you dislike your job, you should work on moving on to a better position. However, you should not take advantage of your employer by not doing your job as best as you can. Your employers will see this behavior and you will risk losing your job.