Mine (ours) is pegging!
I am open minded but not very imaginative, but DH is open minded and experimental.
He pulled out a couple of small toys and lube one night during sex and asked me to use them… on him!
He enjoyed to and we moved up to pegging.
Not something I had thought of before but it is fun to shift the dynamic and he certainly enjoys it.
So, asking the question for some inspiration so I can bring new suggestions to DH.