fresh meat
1. A person or group of people, especially newcomers, who are seen by others as a new target for scorn, humiliation, ridicule, or sexual advances. When you first enter high school, you're often seen as fresh meat—an easy target for thick-skulled upperclassmen. John is a scumbag to women, referring to groups he finds in bars as "fresh meat" for his sexual conquests.
2. Any newcomer or group of newcomers entering into a wider group or organization. Every summer, we get a bunch of fresh meat entering into the company as interns, having just graduated from the local university.