Ah, a question I can answer! I.e., what are tenterhooks.
We go back nearly 20 years, when I was living in Texas and I still was doing actual reporting for the firm I worked for out of Austin. I got asked to cover a 2-week government contract case in Brownsville (with a judge out of Washington who tried to keep kosher, which in Brownsville is a serious challenge). Brownsville, if you look at the map is about as far south as you can get in Texas and not be in Mexico. It was April. It was in the upper 90s every day. :eek: (And as an aside, the AC in my car died an hour out of Brownsville on the way back to Austin, and then I got stopped for 2 hours waiting to get through an immigration roadblock. I gave up and stopped in Corpus Christi overnight; I was just glad I’d purchased 2 bottles of Gatorade before I left Brownsville, or I might not be here today to tell the tale!)
Anyway, enough digression. The case was about shoddy canvas material provided by the government to this contractor to use in making tents. The material had gotten wet and half rotted. And one of the witnesses the contractor brought in was living proof that the right person can make ANY subject irresistibly fascinating. Her specialty, you see, was the degradation of cotton cloth.
That’s right, the degradation of cotton cloth.
She really was an expert; she was one of the folks who worked on the Shroud of Turin. :eek:
Anyway, she was animated. She was excited about her topic. She was so interesting she had every person in the room completely riveted, I kid you not. The judge kept her on the stand most of the day asking her questions. She diagrammed molecules; she described how cotton fibers disintegrate with time; and, pertinent to our discussion her, she described the process of making cloth.
In a nutshell: If you’ve ever looked at cloth on a bolt, you’ll notice that by the woven edges (called selveges), there are (or at least used to be) a series of tiny holes along the fabric.
And now for the answer to your question: That series of tiny holes are caused by tenterhooks! They’re little hooks that would grab the fabric and carry it over an upside-down-V-shaped frame (that kind of looked like a tent, hence the name) as it moved through processing.
I’m not sure that tenterhooks are actually still being used. But every time I hear the word, I remember that amazingly fascinating witness and the day I learned more than I ever thought I’d want to about the degradation of cotton cloth.
Aren’t you glad you asked? 
(And YAY! for new baby, snowbunny! I bet she’s happy to have the kid out of her; she looked like she was about ready to pop when we met her!)