Your dream about being back in high school is quite rich with symbolism and may reflect feelings of anxiety or insecurity about your current situation. Here are some possible interpretations:

1. Anxiety and Pressure: The concern about making it to class on time may indicate feelings of pressure or anxiety in your waking life. You might be facing deadlines or expectations that are causing you stress.
2. Social Dynamics: Encountering only a few familiar faces in class could represent feelings of isolation or disconnect from your current social circle. It may highlight a sense of being out of place or struggling to fit in.
3. Transformation and Decay: The rotten tooth being pulled out might symbolize something unpleasant or negative in your life that you’re trying to expel or confront. Teeth often represent power and confidence, so a rotten tooth could suggest feelings of inadequacy or a fear of losing control.
4. Reactions and Peer Pressure: The act of someone eating the rotten tooth and being praised for it may reflect your concerns about peer pressure or the lengths people go to be accepted. It might also signify a discomfort with how others behave in social situations, especially if it seems unhealthy or inappropriate.
5. Absurdity and Confusion: The nonsensical images on the whiteboard could represent a feeling of confusion or a lack of clarity in your life. It might indicate that you are grappling with complex issues that don’t have straightforward answers.

Overall, this dream seems to highlight feelings of anxiety, social pressures, and perhaps a need to confront uncomfortable truths. Consider reflecting on any current stressors in your life and how they relate to these themes. It might be beneficial to find healthy outlets for your anxiety and to connect with supportive people around you.