This usage often implies a need for secrecy or discretion in watching out for potential threats.

Secretive Alertness

Acting as a lookout is typically an informal, unsanctioned position among peers or groups.

Unofficial Role

Being someone's lookout is a protective role, aiming to keep others safe from trouble.

This phrase is a firm way to assign or acknowledge who is in charge of a task.

It's used to clarify that one is not responsible for another's obligations.

This definition of 'being on lookout' isn't about watching for danger, but about handling a situation.