Source: Starfinder Core Rulebook p.65
When you attempt an initial Disguise check, you can forgo rolling your expertise die. Instead, the first time a creature would pierce your disguise with a Perception check, treat its result as if it had rolled a natural 1 on its Perception check. This benefit applies only once per disguise. At 9th level, this ability also applies against the second creature who pierces your disguise.