Rudeness Rulez is a fun children's card game. The briefest description would probably be 'Cards Against Humanity for children with sentences'. Each player has a hand of cards, each with various words on them. One player then deals a 'start' card which has the start of a sentence on it, and the other players then try and come up with the best ending using as many of their cards as possible.
How rude is it? Not too rude. After all, it's designed for kids! Not all the cards are rude, and the rudest are words like 'poop', 'fart' and 'booger'. The kind of words that kids like to use all the time, basically.