Plays of Shakespeare is similar much of the rhymes and inside jokes are lost now due to modern pronunciation of old words.
Some take this to be a bawdy anatomical pun, expressing the young man's hopes of 'standing' in his lady's 'grass' — a distinction lost nowadays that the pronunciation of "grace" and "grass" have grown so far apart.
(Line 88 of Chaucer's General Prologue, https://chaucer.fas.harvard.edu/pages/general-prologue-0)