Idea where ever since Naruto graduated and became a genin, other fellow shinobi have had to deal with his antics. Each time they come across Iruka, usually at the mission desk, they complain to him about how he should be educating him better and to control "his kid".
Izumo and Kotetsu have to restrain Naruto at the same time one day and whine the whole time they go for drinks with Iruka about how their muscles and entire bodies hurt and how the hell was Iruka able to keep such a kid in check for YEARS.
Iruka dismisses them because surely it's because they're just not used to the orange ball of energy that is Naruto, or that it was just one day in particular that Naruto might've been a bit more hard-headed than usual (he will check with him over ramen tomorrow, just to make sure)
Anko mentions casually how "much of a brat just like you" Naruto is to Iruka, and goes on and on to recall all the fond memories she had of Iruka when he was a little rascal and Iruka just laughs back but does have to defend his boy and point out that she was just as much of a brat if not worse
There's also a day in the mission desk where Kakashi and Team 7 are unexpectedly quiet after a mission, and Kakashi drops dead (well, not dead, but very close) on Iruka's desk. And knowing he doesn't like hospitals, Iruka has to bring him to his apartment and after 24 hours Kakashi wakes up and all he says is a dry and shaky, "I need you". Only to go back to sleep again.
Iruka's face burns red he has to repeat over and over that he probably means he needs help. Help with Naruto. Like everyone else. Especially with how Naruto is with Sasuke and Sakura. Those three are a mess; anyone would need someone else. To help them, that is. Yes. Of course.
If he and Kakashi arrange a little system of "shared custody" where they find themselves alone at the end of the day here and there, drinking or eating together at Ichiraku or one of their apartments, it's nobody's business. Iruka is just helping.
He really, really believed people were exaggerating because they're not used to Naruto's personality and push all the wrong buttons. Until the Fifth Hokage, Lady Tsunade, jokes that Iruka might get a medal of honor for still keeping Naruto in check til this day.
Years go by and most of the village in considerable more familiar with Naruto's antics. Tho! Any new faces he meets will eventually ask him a worn but fond "HOW."
Iruka briefly wonders if he maybe made the third Hokage deal with something similar during his prankster years or being the Hokage gave him the privilege to not hear anything like this.
He remembers how usually he pulled one of his many, many pranks and glitter traps for ANBUs he'd notice the dead chakra zones that were an ANBU or two following him around to stop him from any trouble.
...Yeah people definitely complained about him the way they do now about Naruto.