Are they just joking about drugs?
Are they exaggerating about a beating?
If you have to ask, you have to report it. All teachers are considered "Mandatory Reporters." That means if you suspect a problem, YOU MUST REPORT IT. Failing to do so may result in the loss of your teaching certificate and potential legal actions. If you are wrong, their is no punishment. "Any person who, in good faith, makes a report of child abuse or neglect or testifies in a child abuse hearing resulting from such a report is immune from any criminal or civil liability as a result of such action."
In cases of abuse, your state has a hotline you must call. For drugs and other issues, you are bound to tell a school resource officer or administrator. If you do not know who to tell, EMAIL your administrator asking for advice. NEVER report such things orally, but if you do, follow up with an email detailing the conversation.
As art teachers, if we see something that seems to indicate drug use, self-harm, or violence, we need to report it. I always ask students to sketch first, and I look at this work. If a student included a pot leaf, I remind them it is not school appropriate, and I need to follow up with an email to admin. THEY can choose to ignore it or follow-up.
Why do I always email concerns? Email is admissible in court. A conversation is not. If, god forbid, a child dies, O.D.'s, is hurt, or someone else is harmed because of the situation, and a trail leads back to your inaction, the only thing that will save you is verifiable proof that you did what is required by law.
What if the school does nothing....? Ultimately you have done what you are legally bound to do. If it happens again, you must report it again. This sets up a pattern that can be used to save your butt and prove where the fault should be pointed.
If you feel passionate about a situation, and you truly fear administrative inaction may lead to a serious outcome for a child, you have every right to pick up a phone and make a police report. The law is on your side.
If your employer retaliates for your advocating for a child, document every step of the way, contact a civil rights attorney, and be prepared to win millions in court and retire early.
When in doubt, report it via email.
(Thank you M.U. for the use of the photo and your post that inspired this)