morning glory vs morning tent

morning glory

noun
  • An involuntary erection present upon waking. 

  • Several members of the family Convolvulaceae; climbing plants with trumpet shaped flowers. 

  • A rolling cloud in the shape of a cylinder. 

morning tent

noun
  • An erection a male has upon waking up. 

How often have the words morning glory and morning tent occurred in a corpus of books? (source: Google Ngram Viewer )