To spank means To give a spank or To give a spanking. The gerund, and the progressive (continuous) form of the verb is spanking.
- Example of gerund: "Spanking is good exercise."
- Example of present participle: "She was spanking her son."
Likewise, a series of spanks delivered to the buttocks in quick succession is called a spanking (noun). In the U.K., it is called a smacking if the hand is used, or a caning, birching, tawsing etc. if an implement is used.