Generally speaking, without a written employment agreement, employees in Nevada will be considered to be at-will employees, which means that the employee can quit for no reason and the employer can fire the employee for (almost) no reason. Federal and state law does protect an employee from discrimination and harassment from the employer, but assigning an employee to a work shift will normally be within the employer's rights. The occasional use of vulgar words and belittling comments by an employer are not likely to give an employee a claim to sue on. The hostility must usually be extreme, severe, and frequent before an employee has a claim. If you have evidence of that, you should consult with a good NV employment lawyer; if you do not have evidence of that, you should look for another job.
I am happy to give my "answer" to this question, but please understand that my posting does not mean that you have hired me as your lawyer. Even though I am a real lawyer with a current Nevada law license, I have given my input on this legal question for general information only.