101 Frozen Pops is a catalog published monthly by the Springfield Sperm Bank.
After Selma visited the sperm bank to check into having a baby via artificial insemination, she got a copy of the catalog and looked at it with Marge and Patty. Marge was impressed that the donors included a Nobel Prize winner, an NBA All-Star, and, particularly, one of the Sweathogs. She was less impressed, however, when Selma told her she had checked and learned that the Sweathog in the catalog wasn't Horshack.
Behind the Laughter
The magazine's title is a pun on the frozen snack the pop (called a popsicle in Canada and the USA), the same term's usage as an informal name for one's father, and a reference to the common practice of freezing donated sperm to preserve it for later use.