Pup, Siri could have some explanation.
Apple's notoriously naughty assistant gives a very NSFW response when you ask her to define the word "mother."
The first Sirdits r / Apple Subreddit (h / t Ars Technica) definition of the "mother" of Siri is "short for motherfucker".
We tested this several times and confirmed that Siri actually gives the R-Rated definition when asked for a second definition.
You can see that in the video below (note the language is (obviously, NSFW).)