"... I don't know whether to be impressed or mad."
Iruka was currently standing at the training grounds. The ground was tore up and the trees were uprooted and scattered like twigs. Kakashi's uniform was ripped up to the point that you could see his back and part of his stomach. His mask had a tear in it so you could see part of his cheek. Sasuke was buried in the ground and Naruto was stuck under one of the ripped up portions of ground. Sakura was wobbly on her feet and Sai was hanging upside down from the only intact tree.
A few minutes later, when they had successfully freed Sasuke, Sai, and Naruto then fled the crime scene while being screamed at by Tsunade, found Kakashi another shirt, and managed to nearly strangle Kakashi with a clothesline, they found themselves in Iruka's house with tea and cookies.
"Now, will you please explain to me how the hell you managed to demolish so many trees and put so many scratches on Kakashi without dying?" Iruka cocked his head.
"He was being an asshole! He got us so many D-Ranks missions it took all day and when Sai volunteered to help us to make it go faster, he SABOTAGED THE LAST MISSION!" Naruto pointed angrily.
"Lower your voice and stop pointing. It's rude." Iruka scolded.
Naruto pouted and Kakashi had to resist sticking his tongue out at him.
"Now, how exactly did Kakashi sabotage the last mission?"
"We were supposed to be sending out some letters to help the mail carriers! But he shadow-cloned and shot down every single letter! We had to go and find almost 300 letters in one hour before the people got angry!" Sakura hissed.
"And then when we went to confront him, he LAUGHED AT US AND SAID TO NEVER LET YOUR GUARD DOWN." Sasuke glared.
"Lower voice. Continue." Iruka sipped his tea.
"We declared war on him. We all attacked at the same time. Naruto and Sai used Rasengan, I used Chidori, Sakura punched the ground, and Sai made a huge lion to tackle him from behind. He managed to dodge my Chidori and throw me across the field, destroy Sai's lion, but he wasn't prepared for Naruto AND Sai with a Rasengan. They managed to scratch him up a bit but he dodged. Then, he forgot about Sakura's punch ripping apart the ground and got buried. We thought he was dead until Sasuke got snatched into the ground and Naruto was yanked under a piece of ground. Sai and Sakura got trapped in a genjutsu and they began destroying the field. Kakashi popped up from the ground like some kind of zombie. He was all dirty and his clothes were more ripped but he was fine."
Iruka put down his tea and grabbed Kakashi by the ear.
"Okay, I need to have a talk with your sensei. Stay here."
Kakashi hissed in pain when he was yanked up and dragged into another room.
There was a second of silence and then there was yelling and a loud bang. All you could hear was muffled yelling and loud crashes.
At this point, all the kids were ready to bolt and hope they escaped with their lives. Then, Iruka came back in the room. He looked completely calm and in order despite all the yelling and crashes. The kids stared in horror as he sat down and took a sip of his tea.
"Run." In three seconds, all the kids were up and running straight out the door like the house was on fire. Iruka smirked and went back to the room where Kakashi was paralyzed on the floor with a seal and looking mildly terrified. He had a bump on the head from where Iruka smacked him with a pan. It took a few tries but he finally hit Kakashi and he hit him hard.
"Now sensei~ You're going to find Yamato-kun and help him regrow the forest immediately. It'll take a week without your assistance and I think a week is long enough for you to rewrite almost 400 mission reports from last year that I couldn't read hm? I don't care if you have to beg him for assistance. Get it done."
He ripped the seal off Kakashi, who immediately booked it out the window and went to find Yamato. Iruka smiled. There's nothing as satisfying as scaring people within an inch of their lives and threatening them. Maybe he should pull pranks more often. After all, the thrill is one-of-a-kind.
(Kakashi found Yamato and nearly begged him to help. He has nightmares about Iruka with a pan and refuses to go near one for literal weeks. Meanwhile, nobody dares to mess with Iruka since they saw the famous Kakashi and his Gremlins tremble before him.)
Conclusion: Iruka is the most badass Parental-Figure. He might seem like a weak little Academy Teacher but he can and will scare you senseless to the point where he can make the FEARLESS Kakashi scared of pans for weeks.