DO NOT say you or someone you know is planning a school shooting or terrorist act.
I can't believe I have to say this, but it just happened last game on one of my smurf accounts.
It's not funny. You will be taken seriously. It doesn't matter what context it's in or that you're "anonymous by being online."
I gave an extra report to riot support and will be contacting the police in 48 ours if they don't respond or I get some automated response. (they said they were planning to do it next week.)
The vast majority of school shootings have warning signs or they tell people they are planning it beforehand.
**If you see this behavior in your games, "joke or not", immediately report them and send a ticket to player support. **
Fking. Unacceptable.
EDIT: Riot responded to the ticket and is obviously unable to share any further information. But I'm sure they will handle it from here.