Plagiarism, defined very broadly, is claiming other people's work as your own. At college level, it is severe violation of academic integrity. SU takes plagiarism offense very seriously even if it is not intentional. If your friends say it's okay and no one will find out, please do note succumb to their suggestions! When in doubt, always cite. Give credit to where it's due! There are several resources on this page that you will find helpful.
Take the time to go through the tutorials. It'll be worth your time!
The following videos offer helpful information understand plagiarism and how to avoid it.
This plagiarism tutorial from the Eastern Michigan University, demonstrates how to avoid plagiarism.
From BainBridge College