Postmeditation as well as sitting meditation is symbolized by the syllable AH. AH represents openness and humor—it represents dharma, the truth of the teaching. When we become aware of something, we say AH! People tend to think of meditation practice as a way of calming down and soothing yourself. But in Buddhism there is a sense of AH! You are not trying to calm yourself down—you are trying to be awake as opposed to asleep.
From “Leading a Spotless Life” in The Path of Individual Liberation, Volume One of The Profound Treasury of the Ocean of Dharma, by Chögyam Trungpa, page 225