AtD translation: the unspeakable business with the Rugby blue in hall

[Mike Jing]

P494.25-30   “Oh, old Cyps is all right,” demurred Yashmeen.
       “For a pasty-faced sodomite with no control over his public
impulses, you mean,” frowned Faun.
       “He carries a parasol,” added Lorelei.
       “And the unspeakable business with the Rugby blue in hall.”
       “But he makes me laugh.”

I've found the Wikipedia page for "Blue":

https://en.wikipedia.org/wiki/Blue_(university_sport)

but I still don't know what this sentence is talking about. Any ideas?