A Gnar Skin Idea; Gnarwhal
Much like the Dino Gnar skin, but he would wear the costume of a Narwhal instead in his Mini Gnar form. (If you look up Narwhal costumes, you can imagine what he would look like in one of those.) This skin would punnily be called "Gnarwhal". By the goofy idea, it would be URF/April Fools themed.
His boomerang could be the URF Spatula, his q throwing out the spatula with the particle effects of bubbles or such. I'm not entirely sure what the vfx would be for his w, maybe something along the lines of water themed. While for his E, he could bounce like a seal instead of spinning like in his base animation.
As for his Mega Gnar Form, he'd be an actual Narwhal, flipping about on flippers and making Narwhal noises. He would throw a larger Spatula for his q, and it would stick in the ground for him to pick up. Same thing for the Mini Gnar form jump; He jumps around goofily like a seal. His w would be him slamming a flipper on the ground, and his ult could be him clapping his flippers together to push them away.
All in all, a fun concept I thought of for Gnar, and he definitely fits a goofy idea, instead of a too serious one.