You don't have to be employed in the field of sexual assault prevention to make an impact. Despite the persistence of detrimental and discriminatory histories and systems that normalize and justify sexual abuse, changes are taking place. In order to end the stigma and silence that keep sex crimes hidden, many individuals are working in their communities to develop positive social norms and laws that support justice and safety. We can all hopefully minimize sexual violence by setting an example and promoting pleasant, healthy relationships based on equality, safety, and mutual respect.
Making "harmful" jokes about sexual assault can lead to furthering rape culture so don't make jokes and correct others when they do. Share what you know about sexual assault and emphasize that the victim is never at fault. Inquire politely about the person's attitude if it is disrespectful to survivors. Perhaps talking to them would alter their perspective or belief.