Quicksand Fans

This one is similar to the one posted a couple of weeks ago. There is a sort of inside joke spoken by the Doctor very near the end of "Vengeance on Varos." The character Sil has just had something of a tantrum, to which his aide respond with a water spray. What does the doctor say, to the effect that Sil will need something more? Hint: He says it to companion Peri.

too deep a dive for my knowledge

but i did think you'll appreciate a license plate i saw the other day: DrWhom

OK, here is the answer:

Right after Sil is sprayed by his attendants, the Doctor says, "I think he needs more than water, Perri, eh?"