The Xbox 360's avatars are a pretty stoic bunch, they just stand around all day doing very little. But game developers can put them into games as long as they follow Microsoft's laundry list of what not to do.
Among the acts that avatars can't commit are dismemberment, decapitation, excreting obscene bodily fluids and drug use. What's an avatar to do? Not anything fun, it turns out.
Here's the full, official break-down of avatar actions that will get your game nixed by Microsoft:
Player interacts with their avatar as if it's a separate character
A player's avatar does not have an autonomous personality or instinct. The avatar is under the control of the owning player. It can have idle animations and can respond appropriately to game events but it should not interact with the user as if it is separate from the player, try to get the player's attention in an annoying manner
Violence which causes blood, gore, dismemberment, decapitation, maiming, or mutilation
Cartoon violence is allowed. Violence is allowed as long as there is no blood, gore, dismemberment, decapitation, maiming, or mutilation. An example of allowable injuries includes injuries that might befall an avatar in a sporting event such as American football. Avatars can die temporarily to depict failure.
Player's avatar talks
The player's avatar should not have their own voice. They are allowed to make individual sounds, such as laughing and crying but otherwise cannot use a voice
Acts of sexual innuendo or mildly explicit sexual descriptions or images or sexual posturing
Sexual acts or terminology cannot be insinuated or enacted
Excretes obscene bodily fluids or substances
No sexual or bodily fluids or substances can come from the avatar
Glamorized criminal act
Criminal activities need to be relevant to the story and are presented unfavorably
Acts of an aggressive or threatening manner
Gratuitous insults, bullying, intimidation or otherwise violent or emotional abuse of a position of power are not allowed. Avatars may leave innocents or bystanders slightly injured, but not dead.
Vulgar or profane act
Game-controlled avatars cannot use profane, racist, or discriminatory language, nor can they make obscene gestures.
Use of controlled substances
An avatar is not allowed to hold, be seen around or partake in any controlled substances or paraphernalia including, but not limited to, alcohol, tobacco and drugs
Replace Avatar features
The features of an avatar cannot be hidden or in obscured and cannot be replaced with alternative items. Items such as, but not limited to, masks, hats and alternative clothing, are not allowed
Avatars proportions are not modified
The proportions of an Avatar cannot be modified form their original settings. An Avatar can be resized as long as the proportions don't change