to remove crap or unnecessary items from something i.e. pre-installed software on a new computer
I spent half my weekend trying to decrapify my brand new PC!
to decipher, make sense of, or explain the truth behind any statement or explanation which has been blown out of proportion to the extent of being B.S.
When Bob told me all about the hot girls at his birthday party, Jesse had to decrapify the fact that they were Bob's cousins.