What would it be called? Mine is called Justin's Chocolate Land. Where there's LOADS of chocolate EVERYWHERE. And there's some shortcuts, like in lego racers, if you shoot something, sometimes it opens up and leads to a shortcut. If you use a Koopa shell on the chocolate building on the hill in the middle of the track, there's a star in it, you use it to smash through the next wall, and you just cut a huge circle. Then you fly into a cave, there's a bridge, where down below, a lake of chocolate. Which you don't wanna fall in because it leads to my boiling hot chocolate mugging factory that you race through.

i guess i'd have two options for a mario kart track
- a super awesome mixture of waluigi stadium/bowser's castle with tonnes of jumps and lava and speed boosts
- a full circular track with chomps going around it (like yoshi falls but smaller) and you can drift the whole thing but you gotta dodge the chomps

Mine would be called "Meme Island"
near the beginning mudkipz would come though and try to slow you down
next Weegee would stare you down causing your tires to melt
after wards Robotnik would pout "NO!" making you lose any items
then last Shoop Da Whoop would fire his lazer at you causing the game to crash,
the world record would be 57 minutes and 93 seconds
and IF you win the race M. Bison would say "YESH! YESH!!"

Mine would be a GIANT castle and if you picked up certain items and threw them at a painting on the wall it would open up for a shortcut. And it would also have really long tables of food with loads of speed bosts arrow thingies which you could ride on and collect heaps of food to make you grow bigger and if you grow really big you would be tall enough to jump into cloud world and get all bonus awesome stuff which would also be a shortcut to the end.
Did that make sense?