Clue ins
This is really grey and seems to get muddled with Priming (psychological) often. They essentially have to trigger you in some way in order to prime or clue you in to whatever Operations type stuff they are doing. Could be talking about it in Code Key referring to things in a sideways way, acting stuff out with props. It really depends a lot on the script and the goal of their psyop.
Coughing is common. Door slamming, sneezing, throwing things away. Just general repeating noises.
There are other signals too, for instance if you are about to eat a food item Dosed by perpetrators, someone will typically make a noise. This also happens though if they are merely threatening a dose (or perhaps it could have just been too small or not a noticeable dosage) or a False flag. It has happened before where the food did not actually seem dosed, but they had access to the food and may have simply been threatening to Worry you. Contrarily, it may just have had an affect that was below my awareness. There have also been like benign prank type ones like removing the alcohol from a drink.
I noticed that or it occurred to me that signals out in public are less trustworthy than signals that you receive on a more regular basis from certain sources. So if a source lives near you and is delivering signals, I would say it's probably more likely that those signals can be trusted, rather than