Used by one to say that their friends generally call them by a nickname, and that their interlocutor should feel free to call them that too.

(military) to close ranks (to regroup forces) / (figuratively) to close ranks (to stay united, to make a show of unity, especially to the public; to maintain silence and secrecy in the face of some external threat)

(figuratively) to hold the reins

Les Sables-d'Olonne (a city in the Vendée department, France)

to ring the changes

(informal) to give a kick up the backside (to treat someone a bit roughly in order to motivate them) [+ à (someone)]

(informal) (transitive with à) to give someone a kick up the backside (to treat someone a bit roughly in order to motivate them)

to do the dusting

(figuratively) to shuffle the cards

what a mess! / it's a recipe for disaster! there'll be trouble!