I found it by accident. In a quotation from Shakespeare, in one of those oddball dictionaries.

L in Print and Proverb
1. (in literature) The preyful Princess pierc'd and prick'd a pretty
pleasing pricket; Some say a sore, but not a sore, till now made
sore with shooting. The dogs did yell: put L to sore, then sorel jumps
from thicket, or pricket sore, or else sorel; the people fall a-hooting.
If sore be sore, then L to sore makes fifty sores o'sorel: Of one sore I
an hundred make by adding but one more L. --William Shakespeare, Love's
Labor's Lost, IV.ii.56-61. Wordplay here involves sorel, a deer of the third year;
sore, a deer of the fourth year; L, the Roman numeral fifty.