A Mouse Harp is another name for an Our Monica - you know, the little instrument with reeds that you blow into?
Grendel Briarton is a pen name for (and an anagram of) Reginald Bretnor, who is best known as an artist, but who has also had stories published under his own name.
However, Spider Robinson is to blame for the following:
The weekly pun contest was going on down in the bar. This week, the theme for the contest was Science Fiction. The field of competitors had been narrowed down to two, a man and a woman. It was the woman's turn, and she told this story:
"The Israeli government was delighted when it received a secret communique from an Arab government, offering to negotiate a treaty. When the Arab dignitaries arrived for the negotiations, the Israelis thought it would be a good idea to treat them to some entertainment, and took them to an amusement park. One of the dignitaries particularly liked the carousel, and rode it many times. Unfortunately, he became so dizzy that he fell down when he got off the carousel, and he was immediately eaten by the second of three sheep that happened to be standing nearby.
"The Israeli official escorting the group was horrified. He rushed up to the sheep and said accusingly, 'Middle lamb, you've had a dizzy bey.'"
This story was greeted by a large chorus of groans. However, the woman's opponent protested. Her story, he said, had not stuck to the declared theme of the evening.
The woman smiled sweetly. "The story," she said, "was clearly about Zion's Friction."
She won the contest.