I've never seen 'Silence of the Lambs', but this one, and it's parodied forms, gets my vote as memorable:
"It rubs the lotion on its skin. It does this whenever it's told. "
From Hanibal: "Bowels in or Bowels out?"
The followup line is perhaps even more common: "It puts the lotion on its skin, or else it gets the hose again."
Tossing this into a conversation at certain times can get everyone rolling on the floor, because it's *so* out of the blue and the last thing anyone ever expects.
It was also used to great effect in a "Family Guy" episode. They were doing a "baby trapped down a well" episode, like the "Baby Jessica" case in Midland Texas years ago that got so much wordwide news coverage. Then baby Stewie wanders by, looks down the well at the trapped kid, and out of nowhere says, "it puts the lotion on the skin, or else it gets the hose again". It was such a *perfect* line in context (especially given Stewie's personality), that I had to gasp for breath from laughing so hard.