Do criminal gangs commonly use whistles as signals?

During a recent neighborhood meeting, we were discussing ways to reduce crime. Keep your car locked, porch lights on, things like that. Anyway, one person said, “When you’re outside, particularly at night, listen for whistles. Gangs of housebreakers will post lookouts, who will whistle when they see someone coming.” Everybody else nodded sagely.

But I wonder. Certainly it’s plausible that some gangs use whistled signals. But is this practice widespread enough that, if I hear a whistle outside at night, I have any reason to ascribe it to crimiinal activity? Somehow I doubt that criminals looking for easy burglary targets are that well organized.

It’s common enough. There could be a brief whistle to warn an accomplice or a specific whistle to call one of their fellow members.

Haj

I’ve seen people passing each other on the street communicate with each other using bird-like whistles. Does this mean anything or is it just a social custom I’m unaware of?