ips cells
In Saki volume 5, out of nowhere Nodoka blurted out: "That reminds me. Apparently it will be possible for people of the same sex to have children through iPS cells."
iPS cells are stem cells derived from regular cells. They open up many new possibilities in medical treatments, and of course, human cloning.
Due to Nodoka's remark, "iPS cells" became a tag for pictures of a same-sex couple together with their child. And of course it also applies to any character repeating this line as a parody.
The resulting babies are often referred to as "science babies" or "magic babies".