be on tenterhooks

To be in a state of anxious, excited, or nervous anticipation. "Tenterhooks" (often mistakenly written or pronounced as "tenderhooks") were the hooks on a frame called a "tenter." They were used to fasten stretched cloth to allow it to dry. With the game tied, fans on both sides were on tenterhooks for the entire last quarter. I'm due to find out if I got the job, so I've been on tenterhooks all day! A: "Why is Carrie pacing?" B: "She's waiting for the doctor to call with her test results, so she's been on tenterhooks all day."

on tenterhooks, to be

In a state of painful suspense. The frame on which newly woven cloth was stretched was called a tenter and the hooks used to hold the cloth in place thus were tenterhooks. Tobias Smollett appears to have been the first to use the term metaphorically: “I left him upon the tenterhooks of impatient uncertainty” (The Adventures of Roderick Random, 1748). Clothmaking has changed, and “tenterhook” today survives only in the cliché.