An application of birch twigs to the bare posterior of a miscreant of misbehaving person. The goal of this is to provide an attitude correction. In past years the process was used by husbands to correct their wives, giving rise to old English "rule of thumb" that is you were not legally allowed to birch your wife with a stick that is larger in diameter than your thumb. Sort of counter productive anyway because the best birch branches to use are about 1/4" in diameter and freshly cut so as to be flexible and whippy. The process of birching often requires the woman to prepare her own birch.
In the case of submissive women receiving a birching often gives rise to strong sexual desires and a feeling of contentment and calm.
Elly, I see you have exceeded the budget for your credit card this month. Go cut a switch for yourself and prepare yourself for a birching.