A red warning light triggered by a mom or dad in the area. The triple alarm that goes off mentally when a parent is nearby and trouble may start.
Parent: "Hey! What's with the locked door?"
You: "Just a minute!!"
Friend: "Triple Red Alarm Code M/D! We have an incoming Mom/Dad!"
You: "Hit the power switch!"
Friend: "Got it! Ok, act calm."
This is a phrase used by Northern Ireland folk who use diesel in their car as a cheap way for fuel rather pay for diesel and petrol although this has consequences.
This is phrase is mainly used by farmers and rural folk but can be used as an exclamation.
John: Do you use diesel in your car?
Q-Pat: No, I don't use diesel.
John: So you use petrol then?
Q-Pat: No, I don't use petrol either.
John: What fuel do you use then?
Q-Pat: "(I'm) On The Red".
John: You fecking eejit.