It is a SILLY answer that the Apple programmer decided to insert as an occasional "comeback" from Siri. It has no real meaning other than to be HUMOROUS, to make you smile or laugh. "To shiver with anticipation" means that you are so impatient waiting for the event to happen that your entire body is shaking from the explosive energy of anticipation contained within your body. I've never shivered with anticipation in my entire life. Perhaps a bride might do this right before she walks down the aisle to get married.

Yes, it is indeed a reference to 'The Rocky Horror Picture Show'. The line in question is "I see you shiver in antici... pation.", thus emphasising the wait. Does Siri pause when it says it? As Lee says, this is someone at Apple trying to be amusing. The song is called 'Sweet Transvestite' if you want to listen to it.

I think it's kinda close to goosebump meaning somehow!