*
The first time anyone saw a Bat Challenge was when Dick was ten-years-old.
The main Leaguers were on a video call with Batman, who was in the Batcave. Two years of knowing Batman's little bird, they've seen a lot of crazy and weird things. Some involved Batman singing lullabies, or playing cars, but this increased the Dark Knights immaturity level up quite a bit.
"If we don't do something about this, the press is gonna be all over-"
A shout fruition a familiar voice cut off Flash. "Floor is lava!"
Robin jumping up and hanging onto Batman's shoulders didn't surprise them at all. However, The Batman jumping up onto his chair to cling onto the top of the Batcomputer? Yeah, that'd surprise anyone (with the exception of Alfred, of course).
A few minutes passed, before Dick spoke up. "I think...I think we're safe."
Bruce fell to the ground, landing on his feet. Dick wiped imaginary sweat from his forehead. "Phew, that was close."
Bruce ruffled the birds hair. "Thanks for warning me, chum."
Dick smirked proudly. "Anytime, B."
When Dick bounded away (something about Alfred and cookies), the Leaguers smirked at Bruce, who frowned back.
"Not a word."
The next time Bruce's inner child was unlocked by his son, not only was the entire Justice League, but also the Young Justice team.
It was an open meeting on the Watchtower, at which a bored fourteen-year-old Boy Wonder asked his best pal, Wally West, the single most important question the young speedster ever thought he'd hear in his life.
"Hey. Wanna see Batman humiliate himself?"
"Is that even a question?"
Robin cackled quietly, only his team being able to hear him. They gave him confused glances, which he ignored. He brought out guys wrist computer.
"We don't know how this is, but it is a major concern to both teams-"
"Eh Bats!" Robin called out, much to the Dark Knights dismay.
"Yes Robin?" Bats turned to his protege, a sigh in his voice and an urge to pinch the bridge of his nose.
Robin smirked and hit a button. "Hey macarena!" He sung out, the music playing in the background.
"Crap." Batman growled before, to the surprise and amazement of the teams, doing the dance.
Robin cackled, singing along with the song. "And turn!" He shouted at the part where you're supposed to turn. Bats rolled his eyes and did so.
"Wait for it, chum." Bats told his snickering partner. "Very soon."
Rob had stayed the night at the Mount that night. In the morning everyone awoke to a shriek.
"Robin!" Everyone rushed to his room.
"Wait! Don't come-" Superboy knocked down his door. "-in."
Everyone froze, before laughing, Wally even taking a picture.
There stood the Boy Wonder wearing a unicorn version of his uniform, all pink, purple, and glittery. His mask even had a horn attached to it.
Robin sighed. "I deserve this."
As Dick grew up, the Bats acted less and less like children, to everyone's disappointment. Less jokes were said in the Mount and the Watchtower, and even the Cave. Stories were told to the new generation of Batman and Robins pranks, jokes, and challenges.
After hearing of the macarena Challenge, Tim confronted Dick about why he didn't do that stuff anymore.
"Everyone grows up, Timmy. It's just a part of life. We can't all stay children."
Dick looked at his little brother, who looked down. Suddenly, he felt something. A hope that his baby brother would never grow up and feel the pain, the hurt, the anger, that the world destroyed childhoods with. He suddenly wished that he could go back to his own childhood, the early days of Robin. He suddenly wished that he could've been better with Jason, who left the Earth way too early, about being a child.
About a week after that encounter, the main Leaguers and the team were helping fix a bridge going into Gotham, which was destroyed by the most recent bout of villains who teamed together.
Nightwing looked down at the water, his life passing through his mind. He looked up at his friends and family, landing on Tim, who looked so much older than fourteen, covered in dirt, sweat, and blood.
He looked over at Bruce, down at the water, and then back at Bruce, before smirking, an immature idea popping into his head. An idea that he hadn't thought of in years. Something that he swore right then he'd teach Timmy to do. Humiliate the Bat.
"Batman!" He called his former mentor, a serious expression on his face, gaining everyone's attention.
"What is it, Nightwing?" Batman replied urgently.
Wing smirked. "Whale!"
Batman groaned. "Dang it, Bird Brain!" He shouted, before running towards the edge of the bridge and jumping off on his side like a whale.
Nightwing cackled, something the teams haven't heard in a while, as his adoptive father fell, before splashing into the water below.
"Gotcha! And you thought I was grownup and mature! Hahaha! That's how you do it, Baby Bird!" Wing ruffled Robins hair. Robin snickered a little bit, beaming up at Wing.
Meanwhile, Batman spit out some water, before smiling. "Never grow up, chum. I don't wanna lose my childhood either."