Liar! Liar! is the 10th episode of Season 4 on NBC series Frasier.
LASTING IMPRESSIONS – Frasier and Niles finally admit to their father that they pulled a prank in elementary school and blamed it on another student, who was then kicked out. Martin finds no humour in it, causing Frasier to rethink the deed and go in search of his former classmate to see if his expulsion had a lasting impact on his life.