Dreams often reflect our subconscious thoughts, feelings, and experiences. In your dream, several key elements stand out that may provide insights into your current emotional state or life situation.

1. Train: Trains in dreams can symbolize the journey of life, direction, or movement towards your goals. Seeing your sister struggling with the train door may indicate feelings of concern or a desire to help her navigate challenges in her life.
2. Bully: The presence of a bully, especially one from your past, might suggest unresolved conflicts or feelings of insecurity. It could represent a part of you that feels threatened, or it may reflect external pressures you're facing in your waking life.
3. Civil Retaliation and Note: Your approach to the conflict shows a desire for resolution and communication. Writing a note on a recipe card may symbolize your attempts to express your feelings or articulate your thoughts clearly, suggesting you value constructive communication over confrontation.
4. Hot Cocoa and Friend Sydney: Hot cocoa often represents warmth, comfort, and nostalgia. The presence of your friend Sydney may indicate a longing for connection or support from friends during challenging times.
5. Expired or Recalled Food Items: This imagery could signify something in your life that is no longer beneficial or has past its usefulness. It may suggest the need to let go of old habits, relationships, or situations that are no longer serving you.

Overall, this dream seems to reflect themes of conflict, communication, support from friends, and the need for self-reflection regarding what is beneficial in your life. It may be helpful to consider if there are any unresolved issues with your sister or within your social circle that you need to address. Additionally, think about areas in your life that may require a fresh start or reassessment.