'To bone up on' means to study something hard. It has been used in that sense - particularly in the USA - since the early 19th century. You'll hear it in such sentences as: "I'll need to bone up on algebra before next week's test."
I was aware that 'bone' had other interpretations, Glossop! However - always the gentleman - I did not imagine those were what Bigbird was looking for.
The shoe cleaning bit is very interesting,had no idea they used a bone!!!!!......and that fits in with preparing,as in preparing for an exam....thanks for that,bigbird
"Bone" and "boning" also have the same rude slang meanings in the US you naughty guys are thinking of, tsk tsk. Young school kids usually giggle uncontrollably when a teacher, after making a mistake, says "Well, I really made a boner that time." But Quizmonster's definition is correct (as always!)