mushroom tip vs warhead

mushroom tip

noun

  • The glans penis. 

warhead

noun

  • The glans penis. 

  • The part of a missile, projectile, torpedo, rocket, or other munition which contains either the nuclear or thermonuclear system, high explosive system, chemical or biological agents, or inert materials intended to inflict damage. 

How often have the words mushroom tip and warhead occurred in a corpus of books? (source: Google Ngram Viewer )