Merng – Noun – The action of the testes slapping the under part of ones Bushman-Giggle, encountered during the act of oral sex; the action of the backside of one's hand slightly striking the under part of one's Bushman-Giggle

Merng – Verb – To slightly slap the under part of another’s Bushman-Giggle with one's testes; to slightly strike the under part of another's Bushman-Giggle using the backside of one's hand
You may create a new word using the root word “Merng,” but has to be approved from the framers of “The Book.”

Louie & Tony
Framers of "The Book of Merng"

When someone is giving head, for the man's balls to slap the giver's chin.