As Artificial Intelligence ecosystems become increasingly entangled within our everyday lives, designing systems that are ethical, inclusive and socially just is more vital than ever. It is well known that AI can algorithmic biases that reflect, extend and exacerbate our existing systemic injustices. Yet, despite most teenagers interacting with AI daily, only few have the opportunity to learn how it works and its socio-technical complexities. This is a particularly salient issue for marginalized communities. BIPOC teens are often misrepresented throughout AI development and implementation, but they are also less likely to receive STEM education.In response to these unprecedented socio-technical challenges and calls for more critical approaches to child-centered AI design and education, we explore how we can leverage co-speculative design practices to help scaffold BIPOC youth (ages 14-17) critiques of existing AI systems and support the re-imagining of more just AI futures. Drawing on Harway's Situated Knowledges and Speculative Fabulations, these workshops highlight the unique ways marginalized youth perceive AI as having social and ethical implications and how they envision alternative worlds with AI. Our case study describes three 2 hour sessions of a larger 8 week black-led AI STEM program. Analysis includes, data from pre-post surveys, workshop recordings, focus group discussions, learning artifacts, and field notes. We contribute 1) a discussion of how youth perceive AI as having social and ethical implications, 2) a nuanced understanding of how speculative approaches can be leveraged to support youth engagement with complex socio-technical issues and 3) enable youth to open up new AI possibilities in a world absent of techno-capitalist values.