Nettle : noun THEortie is an edible herbaceous plant whose leaves are covered with fine hairs that contain an irritating liquid.
Do not push grandmother (granny) in the nettles: do not exaggerate (see below).
The expression "You mustn't push grandmother / grandma / grandma in the nettles": You must not exaggerate, abuse, exceed the limits - You must not behave asocial with someone.
If the image is clear, the origin of the base expression do not push for you must not exaggerate seems unknown although its appearance is generally located in the first half of the twentieth century.
If the image is clear, the origin of the base expression do not push for you must not exaggerate seems unknown although its appearance is generally located in the first half of the twentieth century.
Anyone who "pushes" too much, in fact, risks doing damage by pushing or crushing what he is pushing. The original metaphor is therefore unambiguous.
The addition of grandma is there to reinforce its meaning. Its funny side makes its use more frequent than do not push the plug too far which has exactly the same meaning.