Swear Word of the Week and the Insult of the week from the former Techfoolery podcast show. The podcast show is no longer running, but this is still a great collection of swear words and insults from the great Ashley Esqueda and James Bricknell.
It also supports adding the Ashley and James avatars as widgets on your home screen or lock screen to get quick access to the swear words.
The app is completely free and there are no ads. Note that it contains adult language and may not be suitable for children.