shenanigan: trickery; nonsense; fooling around
This slang word has been around since at least the middle of the nineteenth century. The first uses usually carry the meaning of cheating or fooling. Mark Twain, who is credited with popularizing the term, wrote in an 1862 letter, "Consider them all . . . guilty (of 'shenanigan') until they are proved innocent." Early spellings include shenanegan, shinannikin, and shenannigin . More recently, the word is almost always used in the plural, and seems to carry the general meaning of getting up to no good. For instance, New York magazine for April 3, 1978 describes House Calls as "a film . . . about medical shenanigans in and out of a hospital."
The word's origin is obscure, although it evidently first appeared in the United States. A number of word historians have noted that it has a vaguely Irish sound, but no one has found a likely Irish ancestor for it.