Dreams involving water, especially in the context of floods, often symbolize emotions and the subconscious. In your dream, driving through a flood could represent navigating through overwhelming feelings or situations in your life. Leaving your grandma's house may suggest a transition or a desire to reconnect with family or past experiences.

Picking up the couple indicates a willingness to help others or perhaps a desire for companionship during challenging times. The bearded dragon symbolizes your personal interests or aspects of your identity. Having the girlfriend hold your pet may reflect your relationships and the dynamics within them, particularly how others perceive your interests.

The incident with the bearded dragon peeing on the girlfriend might signify unintended consequences of your actions or how your personal choices affect others. Dropping the bearded dragon into the flood could represent a fear of losing part of yourself or your interests, while the group of iguanas might symbolize the emergence of new aspects of yourself or new experiences that arise from emotional turmoil.

The moment when the iguana jumps out of the water and scares you could reflect your reaction to unexpected changes or surprises in your life. However, your shared sense of wonder with the boyfriend suggests that you are learning to embrace these surprises and challenges.

Overall, this dream highlights themes of transition, emotional challenges, relationships, and the acceptance of new experiences. Consider reflecting on your current life situation and how you handle emotions and relationships, as this may provide further insights into the dream's meaning.