Breadcrumb
From SA Mafia Wiki
A Breadcrumb is a hint made early in your post history indicating your role and/or night results. For instance, a post where the first letter of each sentence spells out "COP" is a classic role breadcrumb.
Breadcrumbs can be used to allow a town power role more credibility if they ever have to roleclaim, since it indicates they planned on being able to claim that role well in advance. Scum players, conversely, tend to modify their fakeclaims as the game goes on and they learn more about the setup, and thus are less likely to breadcrumb since it locks them into a particular claim early in the game.
Breadcrumbs can also allow power roles to indicate their results in case they are ever nightkilled before they can tell the town. For instance, if a flipped Cop is found saying, "I really think Player is scum, call it a hunch", that is likely a breadcrumb of a scum investigation against the Player.
If a breadcrumb is too simple it risks being too obvious, and thus risks the player exposing themselves too early (the equivalent of a softclaim). But if a breadcrumb is too complicated, it risks being less believable (in case of a role breadcrumb) or being unseen (in case of an action breadcrumb).
Note that breadcrumbs must be man-made; computer-assisted encryption is against the standard mafia rules.