On demand user-invokable (realtime) relay ignore

[InterLinked1]

Rather than static rules for blacklisting certain things to not relay from IRC to Discord (or vice versa), would be nice if there was a way that users could manually specify not to relay messages to the other side.

e.g. from IRC:
/norelay bob: hey, what's up?

^-- wouldn't get relayed over to Discord, etc.

The particulars of whether there is a standard IRC command to do this or it could be parsed some other way, I don't care too much about, but would be nice for certain messages that maybe a user wants to be "IRC only". I think changing nicks to something on the blacklist and back again would work, but that's a lot of trouble just for that.