red rag n.
1. [late 17C–late 19C] the tongue; thus too much red rag, speaking too long and too loud, give the red rag a holiday, be quiet, stop talking, wag the red rag, to talk to excess [its colour and its ‘flapping’].
2. [late 19C+] a menstrual cloth or sanitary towel.
unrestrained, critical speech.
[early 19C–1900s] to menstruate.
[19C] to blush.