John Cowan blogged the infamous case of the "ough" words which is the standard example of how much of a tricky jackal English can be to poor ESL (EXL?) students. By coincidence this is just a day after I ran into "List of unusual English words in the LaborLaw Encyclopedia" (strange provenience for such content). One of the entries in on that page is the infamous "ough" gang, but there is also a lot of other really interesting Engligh trivia, some of which I've come across, and some of which I haven't, but all of which makes for fun reading. One thing did surprise me. I'd always carried "set" in my head as the English word with the most definition, but this page has it as second, after run (76 to 63), based on the OED. I wonder whether my memory was from a discussion based on another dictionary, or perhaps is was another measure such as longest actual line count for the dictionary entry.
BTW, re: the title. Back in secondary school a bunch of us were riffing off the joke of spelling "fish" "ghoti", and had a competition for who could come up with the coolest words only based on the crazy phonetics of the "ough" gang. "ghough" was one of the entries (mine, if I recall rightly), pronounced "few". There are some even cooler ones, but I leave those as an exercise for readers and commenters. You can use Cowan's list as a cheat sheet (he keeps things a bit simpler than the LaborLaw page).