Can't search (on SO, with Lucene) for R language's %in% (set membership) operator, even with quotes. (Note that Lucene's default behavior without quotes is even worse than returning no hits, it strips both '%'s and gives tons of irrelevant hits.)
Here is one such answer which cannot be found by searching for '%in%'
(It's in Jouni's answer, admittedly inside a <code>
tag)
Note that I'm searching for %in% , not the %+% in the title of that question.
PS: as ever, I'm not expecting this ever to happen, just letting R users know:
Bad clunky workaround: search for [R] "set membership" operator
UPDATE: fixed end 2012