The phrase "to toss a grenade" means to create or introduce a situation or statement that causes chaos, conflict, or disruption. It is often used metaphorically to describe someone stirring up trouble or controversy. Full definition
The executive order tosses a grenade into efforts to find safe havens in the United States for scholars displaced by the civil war in Syria and simmering conflicts in Iraq and Yemen. (sciencemag.org)
We're pretty sure that tossing a grenade out of a hotel window in Istanbul will bring the cops around (at the very least), so putting pants on might be prudent. (themarysue.com)
About that time, the mayor tossed a grenade into Doctoroff's plans to establish a bottom - line sensibility: He decided to buy BusinessWeek. (fortune.com)