At first I thought it was yum-seng, sum-seng, poh-seng..but no..he insists..it's kum-seng.
He usually says, "Mom, you are so kum-seng!" when I make a blunder,
..which makes me think, the word is equivalent to chimakan in our language.
...I think kum-seng is inspired, derived or originated from the name poh seng. Whoever he is. *shrugs