Book In-Jokes in...
Finite Dimensional Vector Spaces
(from “Math Words & Other Words”): “G. P. Hochschild worked with Halmos at the University of Chicago, and on hearing that Halmos was writing a book asked if his name would be in the book.”
And indeed, on page 198 we find the index entry:
Hochschild, G.P. 198Special thanks to Alon Amit for contributing this item.