Something along these lines, I shouldn't be surprised.
5 seconds sound clip from the Mary Poppins movie soundboard.
You can hear this line at 00:39:15 in the Blu-ray version of the movie.
Quote context
[...]
- To the park? Not if I know Mary Poppins. Other nannies take children to the park.
- When you're with Mary Poppins, suddenly you're in places you've never dreamed of.
- And quick as you can say Bob's your uncle, the most unusual things begin to happen.
- I'm sure I haven't the faintest idea what you're talking about.
- Something along these lines, I shouldn't be surprised.
- Punting on the Thames. That's always good if you like an outing. Here we go.
- The circus. How about a lovely circus? Lions and tigers.
- Oh, that's lovely. If you please, I'd much rather go there.
- Beautiful, ain't it? A typical English countryside as done by a true and lovin' hand.
[...]