S02E51: Party Animals

Grandpa Lou tells the Rugrats about Aladdin and his magic lamp, so Angelica and the other Rugrats make a wish on a real lamp. When it doesn't work, Angelica falls asleep - but the babies stay awake for the grown-ups' costume party where they think that all their wishes came true. By the time they tell Angelica, the party's over and she doesn't believe the babies.