как с гуся вода {adv. phr.}
kak z gusya voda
{literally} like water off a goose.
Without producing any effect; without paying the slightest attention.
Как с гуся вода, с нашей девочки худоба. — Like water off a goose, the illness off our girl. — from an old spell.
Comp.:
like water off a duck's back
хоть бы хны
по-барабану
до лампочки