Rashi, Babylonian Talmud, Sanhedrin 73a, s.v. delav orheih
רש"י מסכת סנהדרין דף עג
דלאו אורחה - ליבעל, ואיכא בזיון ובשת גדול
It is not his way to be penetrated by a male, [one may kill the pursuer to prevent] great shame and embarrassment. [Translation by Rabbi Steven Greenberg]

Suggested Discussion Questions:

What sort of shame and embarrassment do you think Rashi is referring to?

Time Period: Medieval (Geonim through the 16th Century)