Second Impression( Complete Scoundrel, p. 88)
[Interaction, Skill Trick]
You can convince someone of your false identity even after your disguise fails.
If an observer sees through your disguise with a successful Spot check, you can (as an immediate action) attempt a Bluff check to convince him that he's mistaken. Use the observer's Spot check result as the DC for your Bluff check; if you succeed, the observer ignores the evidence of his own senses in favor of what your disguise attempts to show.
You must be aware of the observer's discovery in order to use this trick; for example, you can't use it against someone viewing you secretly, nor can you use it against someone who sees through your disguise but keeps that information secret. When in doubt, the DM should allow a character to use this trick if she has any reason to fear that her cover has been blown.
You can use this trick only once per day, but its effect extends to all viewers within 30 feet of you. For example, you could attempt it against an entire patrol of guards confronting you just as effectively as against a single person.
This trick doesn't let you maintain a disguise that has been defeated by other means; for example, if your disguise self spell is penetrated by a true seeing spell, Second Impression won't help.