the shenanigans flag
A term used to point out or call out a clear and obvious social mistake on the part of others.
"I'm throwing down the shenanigans flag, that chick should not be out with that doofus"
or
"I'm throwing down the shenanigans flag! Why the hell were you cockblocking?!"
or
"I'm throwing down the shenanigans flag! Why the hell were you cockblocking?!"