A Dirty magazine (スケベ本) is a type of book with images mostly involving women completely in the nude or performing pornographic acts while nude.
Master Roshi has a huge collection of them, which he is commonly seen viewing throughout the series. Ninja Murasaki of the Red Ribbon Army is also seen to have a collection hidden in a hut on his floor in Muscle Tower. It is also revealed that Dr. Brief collects them, even though he is married; Bulma accidentally switches capsule cases with him and ends up seeing the magazines in one of the capsules in it during the General Blue Saga.
Krillin gave one of these to Roshi in order for him to take him as his pupil. Krillin had several more that Master Roshi found after Krillin fell through the Flying Nimbus. In "Until We Meet Again", Krillin berates Roshi for still reading them, only for Roshi to respond that Krillin reads them as well.
In Dragon Ball Super, after the third destructive shockwave produced by Goku and Beerus' Energy Clash Old Kai shows Kibito Kai one of his Dirty magazines depicting a scantly clad blonde woman as a final goodbye (as he believes the universe is about to end), only for Kibito Kai to knock it away in anger to Old Kai's shock.
Video game appearances
In Dragon Ball Z: The Legacy of Goku, the magazines must be collected and returned to Roshi at the beginning of the game. In Dragon Ball Z: Budokai, a magazine can be seen laying on a table in front of Kame House in the first level's opening cutscene. The cover of said magazine cannot be seen, but with emulator tools, the game camera can be moved to see that the cover is, unsurprisingly, a nude woman (albeit blurry). In Dragon Ball: Origins, Krillin uses the dirty magazines as a bribe to become Master Roshi's student, just like he did in the anime/manga. In Dragon Ball: Origins 2, in the bonus level 3-5, Dr. Brief wants Bulma to retrieve the dirty magazine capsule Bulma left on General Blue's Camp island; it is revealed in this level that the magazines were found by Master Roshi, who hid them on the island because he can't read them at Kame House. They appear under the title Naughty Book in Dragon Ball Z: Legendary Super Warriors.
- A magazine that features males was among the dirty magazines Krillin gave to Master Roshi. The word "Homo" can be seen on it.
- Bulma is extremely embarrassed that her father collects them despite the fact he is married.
- In real life, it is not uncommon for married men to collect dirty magazines.
- In the same scene, Goku also expressed confusion about why the girls were naked and yet not taking baths, and also feeling sorry for them when he thought they were too poor to afford clothes, owing to his more innocent nature and thus not understanding what was actually going on in the magazine.