Neologism: @here grenade
@here grenade - noun phrase - The act of tagging a message @here (meaning, everyone) in a crowded Slack channel (users >= 100), causing everyone who's busy but monitoring to drop whatever they're doing and flame you for bothering them by messaging @here. Normally done by a user trying to get a response to a maximum severity ticket that's been ignored for longer than the SLA.
Example: "PFY threw an @here grenade into the #tech-support channel because the border router was on fire and the admins on call were ignoring their pagers. He got kicked but at least the outage is over."