The answer is hazing.
Hazing refers to any activity expected of someone joining or participating in a group that humiliates, degrades, abuses, or endangers them, regardless of the person's willingness to participate. It is often associated with initiation rituals in fraternities, sororities, sports teams, and other organizations.
While initiation violence could describe violent acts during initiation, it is not a commonly used term. Hazing is the more precise and widely recognized term for such activities.
Civil harassment generally refers to a pattern of behavior that causes someone to feel threatened, intimidated, or harassed, but it is not specifically tied to organizational initiation processes.
Peer pressure involves the influence exerted by a peer group to encourage someone to change their attitudes, values, or behaviors to conform to group norms. While peer pressure can be a component of hazing, it is not synonymous with the violent and discomforting acts described in the question.