Dreaming about getting ready for a birthday party late at night, especially with your parents, can have several interpretations:

1. Symbol of Celebration: Birthday parties often symbolize new beginnings, celebrations, or milestones. Your dream might reflect a desire to celebrate something in your life, or it could indicate that you are approaching a significant change or personal growth.
2. Feeling Unprepared: The fact that you are getting ready late could suggest feelings of being unprepared or rushed in your waking life. It might indicate that you feel you are not fully ready to face certain situations or events.
3. Family Connection: Being with your parents in the dream may highlight your connection to family and the support system they provide. It could indicate that you are seeking guidance or approval from them regarding a decision or event in your life.
4. Nostalgia: Attending a birthday party can also evoke feelings of nostalgia. This dream might be a reflection of your childhood memories or a longing for simpler times when celebrations were more carefree.

Consider how these themes resonate with your waking life and if there are any upcoming events or emotions that might relate to your dream.