Something has tripped her trigger, so to speak, especially considering the surprise element.
If she doesn't chat online or text with others, I'd guess that this came from "hot talk" between her and her lovers when she is with them. I'd doubt it was something she came up with by herself, so, again, I'll guess that idea was planted in her mind.
Now... I encourage you to explore this with your wife. My personal opinion is that using a dildo so large that it requires a ball gag for the first time experience is NOT a good idea.
Starting off with something more modest in size is recommended, and there is so much to do, experimenting with different positions, how far she penetrates, pacing, that it will keep you occupied for quite some time. By then, you will have a much better idea of what works well and whether an increase in size is needed.
With that in mind, I'm confident you will LOVE it! My opinion is that most men love it, although they may not admit it. I know that I do.
My wife used a variety of toys (or fingers) in my ass over the years. I think I enjoyed it more than her; I used to beg her to fuck my ass.
It was never anything too wild, and the biggest dildo she used on me was about 6" (15cm) and 1.5" (4cm) diameter. She couldn't pound it all the way in over and over, but if she did slow strokes, I could take all of it easily. When I was ready to cum, I didn't mind trading the slow strokes for faster fucking and less penetration.
I also have a GF that has dildos that are 8-9" (20-23cm) and the shaft is tapered from about 1" (2.5cm) at the head to 2" (5cm) at the end.
Before we met, she had declared that she WAS going to fuck me with one, and I kept telling her no way, she would never be able to get it in, etc.
When the time came though, she was determined, and used enough pressure to force it in. I was quite surprised she indeed penetrated me, and she had to take a bit of time, but she fucked my ass good with it!
She did make me take all of it, although it was only for a second because I couldn't take all of it, but she was making a point about her being able to make me take it all. Other than that, she was using about two-thirds of it.
We started off in missionary (me on bottom), I had to bend over the edge of the bed for a few minutes, and ended with me ass up/face down on the bed.
It not only felt good, and made my dick get hard, it also made me leak precum heavily until I shot my load involuntarily. I wanted to cum, but didn't have to jack off to achieve that.
Another 'trip' was the gape. I couldn't see it, of course, but I could feel it, and she kept exclaiming how opened up I was, she had never seen anything like that before, and she kept my cheeks spread open, wiggling a finger around while watching it slowly close.
So that's my experience. She now has a strap-on, and I can't wait for her to fuck me with that. Having both of her hands free should be much better...
