At the Tarouzakura viewing party, Ataru gives Lum a piece of food from his box-lunch, and she gets angry after tasting it, yelling "What did you feed me?". He had slipped her an umeboshi (pickled plum), which he found out in TV episode #65, makes Oni people intoxicated. He fed it to her as a prank, like some teenagers do at parties when they spike the punch.
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