"jak tirk ler kbal dtear"=pour water over a duck's head is equivalent to saying "go in one ear and out the other" because when you pour water over a duck's head, the water does not stick to its head (the words said to a person does not stick)...
btw ear in khmer is "tro-jiek" (jak tirk ler tro-jiek

) which totally does not make sense
and sorry, I don't understand your khmer-lish...
here's another one:
"tver bonn ban bonn, tver baab ban baab"= "do merit, get merit, do sin get sin" which basically comes close to the English equivalent of saying "what goes around comes around"