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In the North American release, the game came with a pin-up poster featuring a blonde woman using the pole holding up a BMX bike cushion to pole dance on. The size of the pin-up varies with each port of the game, with the GameCube version's being double the size of the rest as the back side of it features a map of the game's first area, The Bronx, NYC.

However, that's not the only pin-up to come with the North American release of the game. The cover art is reversible, and if you flip it over to the back side you will find a pin-up of a redheaded woman in lingerie sitting backwards on a BMX bike, with tattoos of logos for the game and for the AKA Acclaim brand on each of her buttocks.
Contributed by MehDeletingLater
The box art for the Xbox and Gamecube versions feature a stamp that says "Keep It Dirty." This was removed from the PS2 version, most likely due to the fact that the PS2 version is censored, removing all nudity for the game.
Contributed by Takahashi2212
NSFW - This trivia is considered "Not Safe for Work" - Click to Reveal
In all Australian releases and the PlayStation 2 NTSC release, there is no option to alter custom rider breast size. There is also no option to have the rider be topless, thus removing all nudity.
Contributed by ProtoSnake
BMX XXX was originally to be the third title in the Dave Mirra series, however when Acclaim started to make the game more adult-oriented, Mirra filed a lawsuit against the publisher claiming the title damaged his image and that his likeness and name were still being used with the game promoted as "Dave Mirra BMX XXX" even after he had separated from the project. According to Mirra, the game was supposed to be a mature, tongue-in-cheek game similar to the film "Airplane!".

The project was instead split into two with the second game "Dave Mirra Freestyle BMX 3" being released for the Game Boy Advance.
Contributed by KnowledgeBase