a ghost is clear and a vampire (biter of throats) can't be seen in the mirror
Chappelle Show had a skit mocking MTV's show Making The Band. Chappelle, acting as original show cast member Dylon, continuously repeated the phrase "I spit hot fire".
Ichabod Crane is the character who was the Headless Horseman in the novel The Legend of the Sleepy Hollow. Lupe is metaphorically like Ichabod Crane because he satirically claims to not have a brain, in other words making fun of dumb rappers.