The substance Acrimonium and its effect is named for the word "acrimonious", meaning "angry and bitter, especially in a speech or debate". It is one of Grandmama's medical potions specifically designed for helping overly perky people get back in touch with their Id/"Dark Side". As Grandmama herself stated in, "It could turn Mary Poppins into Medea!"
Grandmama, while insisting to a depressed Pugsley that he should be happy for his sister Wednesday getting a boyfriend, reveals the existence of acrimonium to him. Grandmama tells Pugsley to stay away from that bottle, but he steals it from her, planning to use it to "cure" Wednesday of her lovesickness and get her back to torturing him in the sibling rivalry he enjoys.
The plan is set into motion in "Full Disclosure" when the family and their guests play a game that involves sharing their deepest darkest secrets at the dinner table while passing around and drinking from The Sacred Chalice. Pugsley slips the acrimonium into the chalice right before Wednesday's turn, but Wednesday passes the chalice to her boyfriend's mother, Alice, when the woman has a coughing fit. Once she swallows the acrimonium without knowing it, Alice, normally living in denial laced with poetry and smiles, expresses her true innermost turmoil in the song "Waiting" when she admits that her husband Mal and his workaholic tendencies make her wait endlessly for a spark in their relationship that is no longer there, and she feels that if that doesn't change she'd have nothing left to wait for but death itself. This shocks everyone at the table, as Gomez Addams states that Alice's full disclosure is "too dark, even for our taste." Chaos ensues in part because of this revelation. Pugsley is busted for stealing and using acrimonium from Grandmama's medicinal stash, but he is let off easy because his actions had mended the bonds of two different families.