The Brief: Being "caved in" means that someone is feeling overwhelmingly in their own head after ingesting marijuana.

Bluesquiggle
DEEP DIVE

As cannabis can cause introspection, caved in describes the feeling of having too much introspection, and potentially having a “bad trip” from smoking weed.

This M-E-D* it feel caved in – Travis Scott, “Carousel”

*In this case, M-E-D refers to medical marijuana.