The whole series is dementially fun, but some moments are even funnier.
Rat-Man's Negated Moment of Awesome in his Origin Story, setting the tone of dementiality for the entire series. The Buffoon (a Shallow Parody of Jack Nicholson's Joker) had kidnapped an orphan and demanded a ransom from hisparents, and Rat-Man had decided to free him. After a rough start, Rat-Man curbstomped the Buffoon's gangBatman style (save for the moment he pulled a gun on one of his men, but he didn't fire), moved to confront a terrified Buffoon... And paid the ransom. The Buffoon was too shocked to even move long after Rat-Man and the kid had left...
In one story, a bedridden Rat-Man told Arcibaldo he had never read a book in his life because Chuck Norris would appear and take him on a mission every time he opened one. Of course Arcibaldo doesn't buy it and leaves disgusted, but then...
Rat-Man opens the book Arcibaldo gave him
Chuck Norris: "Get up! There are smugglers to stop at pier 13."
In the early story "Immutable Doom", Rat-Man reached a monastery in Tibet, having heard they would forge invincible armours. The monks explain him they do, but only if you fail into controlling your mind, as succeeding in that would actually make you invincible, and any outburst of rage would be punished with a piece of armour, and then assign him as a room mate to a former scientist who came there to quash his hate and rage, and had not a single piece of armour on himself. The former scientist's name? Victor Von Doom. Three guesses on why, by the end of the story, Victor had a full armour and got kicked out.
At the end of the story, Rat-Man is a day late into delivering cosmic rays-proof shielding to a spaceport, shielding that should be installed on an experimental spaceship whose launch has been postponed. The spaceship's builder? Nobody important, some doctor named Richards... Who hijacked the ship and launched it before Rat-Man's eyes.
During issue #104 Brakko and Jordan are talking about Brakko having two days to arrest Rat-Man, and Jordan explains that if he had to arrest a friend he'll tell him to run and count to 20 before giving chase, knowing that, having trouble remembering what comes after 12, he'd give him a huge headstart. Later, we have this situation: