Often used in a phrase, "stuffed up" or "stuffin crazy," the word stuffed is used in place of the word Fuck. Therefore, it can take the shape of a verb, noun, adjective, or any other part of speech.
"Yo guys let's get stuffed up!"
"Are you guys stuffin around right now? be serious, like what the stuff guys."
"Yo stuff you!"
"Are you askin to get stuffed in the ass?"