The Collaborative International Dictionary
To be a tiptoe
Tiptoe \Tip"toe`\, n.; pl. Tiptoes. The end, or tip, of the toe.
He must . . . stand on his typtoon [tiptoes].
--Chaucer.
Upon his tiptoes stalketh stately by.
--Spenser.
To be a tiptoe, To stand a tiptoe, To stand on tiptoe or To be on tiptoe, to be awake or alive to anything; to be roused; to be eager or alert; as, to be a tiptoe with expectation.