Chopperman

In a short, one-shot story by Eiichiro Oda, entitled Chopper Man, Chopper is depicted as a superhero, with members of the Straw Hat Pirates featured in various different roles (mostly villains). The story parodies the superhero, and super sentai genres, as well as One Piece itself. The characters are as follows...

Chopper Man
The hero of the story, who uses his Chopper Cape to fly and save the world. Although he can fly with the cape, he also has a private jet, called Air Force C but doesn't ride in it as its just a model. His ultimate weapon is his cuteness, which he uses through his ultimate attack, the "Kyuun Spark". If his enemy doesn't care about cuteness, he will resort to "Chopper Violence".

Namifia
Chopper Man's "lovely assistant", who is based on Nami. Resembling a secretary, with glasses and a wireless headset, she appears to be Chopper Man's manager. Namifia is greedy like her alter ego.

Dr. Usodabada
The main villain and "embodiment of evil", based on Usopp. Aside from looking exactly like Usopp, Dr. Usodabada is dressed in a doctor's coat, with a cape, and a handlebar mustache. He resides in an evil castle, with comically bent towers, with cliché'd lightning crashing behind it.

Giant Luffy Bomber
Based on Monkey D. Luffy, the Giant Luffy Bomber is a giant robot, stationed outside of Dr. Usodabada's castle, and acts as his secret, ultimate weapon. In the story, however, Chopper Man befriends it, and the Luffy bomber destroys Usodabada's castle. The Luffy Bomber appears to be covered in various guns, a possible reference to his attack names. Namifia sold it for jewelery.

Usodabadan Three Villains
Although they never appear in the story, they are referenced in the intro. One of them resembles Sanji in a lizard suit, called "Ero Monster, Sanjilops". He claims he is not a pervert but thinks about perverted things and has three cigarettes. Zoro is represented as a monster with a fundoshi, the number "1111" across his chest (which could be two "11"s), a metal nose similar to Franky's, and an onigiri for a head (an obvious play on his signature attack), named "Onigiri Mystery Man, Zorogilla". Robin is shown as a scantly clad warrior queen, named "Flower Mystery Woman Robiflowan", with six arms, and large flower petals adorning her helmet. She is always affected by the Kyuun Spark.

Trivia
The short is referenced in the Ending sequence with the song "Aventure World", wherein Chopper adorns his Chopper Cape, and flies around, eventually off-screen. The story was also made into a One Piece television short, which aired at the end of episode 279.