Pronounced "UHFCK", not "YUFCK" as some commonly pronounce it. The pronunciation "UHFCK" is more practical especially when conversing in public, since "YUFCK" sounds too similar to the original and vulgar word, "fuck", and is slightly akward to pronounce. This is also because "UHFCK" is one syllable, as are most other commonly used obscenities, whereas "YUFCK" is two.
An invented word, believed to be originally introduced during an incohearant MSN chat conversation, when the creator intended to write three consecutive "fuck"s, but mispelled one as "ufck" accidentally(fuckfuckufck). Later, said person and their chat partner realized that it was a rather practical word to substitute the word "fuck", and from that day on used it in everyday conversation in place of it. It is slowly beginning to catch on in other people's everyday conversations, with some people already accustomed to saying it in place of it's vulgar counterpart involuntarily when they talk.
Furthermore, ufck is just as veratile as fuck, able to take on almost any suffix to adjust to whatever situation it needs to be applied to at the time.
"That's ufckin' crazy."
"Man, we really ufcked up today..."
Richard: "HOLEEEYY MACKERALL GUYS!! GUESS WHAT I JUST SAWWW!!"
Kevin: "Shut the ufck up!"