The Firesign Theatre is/are hard to describe; perhaps an anal analogy might help:
"Bob" : Cthulhu
Firesign Theatre : Great Old Ones
Or maybe this podcasting blipvert:
The Grammy-nominated anarcho-satiric comedy troupe Firesign Theatre offers audio clips from their new and classic albums and radio performances. The Future Fair! You may already be there!
Or maybe the fact that Rev. Ivan Stang worships them.
In any case, everyone lock your wigs, let the air out of your shoes and prepare for a period of simulated exhilaration!
The lexicon might help confuse you further.