Street slang for PCP
(that's angel dust
, kids). The term seems to be most commonly used in hip-hop
Alternatively, a cigarette or joint dipped in embalming fluid.
In both cases, it's not exactly good for the body and mind. Thus, the phrase "Are you smoking sherm?" is sometimes used in place of the much more common "Are you smoking crack?" when the speaker is questioning the sanity of his or her audience.