My friend looks at me totally blankly.

And people would look at him blankly and say,

So, I was sitting there staring blankly at the air

It was so uncanny to Henfrey that for a minute they remained staring blankly at one another.

And suddenly and most wonderfully the door of the room upstairs opened of its own accord, and as they looked up in amazement, they saw descending the stairs the muffled figure of the stranger staring more blackly and blankly than ever with those unreasonably large blue glass eyes of his.