Stereotyping is an excellent topic for an illustrative thesis as there are many examples within culture and the media to pull from. It is a good idea to focus on one type of stereotyping (such as racial or gender) and look for examples of this type in the media. For example, you could focus on the stereotyping of women as housewives and use examples from commercials for cleaning products that feature only women.
You can illustrate patriotism by giving examples of what it means to be patriotic. You can focus on visual symbols of patriotism (the flag, bald eagle, etc.) or on actions that are considered patriotic (supporting the troops, for example).
Unethical behavior is a broad concept that can have many different meanings. Illustrate what unethical behavior means to you by describing examples of it either drawn from personal experience, your prior reading or the media. You can narrow your thesis by focusing on a particular set of unethical behaviors in business, such as creating misleading advertising.
Illustrate the idea of discrimination by giving examples drawn from personal experience, history, or the media. For example, you could focus on racial discrimination and give examples such as the policies that forced African Americans to attend separate schools and barred them from being served in certain restaurants.