A company, mainly YouTube-based, that promotes dubstep, drum and bass, and general EDM. Lots of subscribers, and those who are into the more mainstream part of what's called dubstep, for example Nero and Skrillex, love it - while others who prefer the underground, "true" dubstep despise it and think of it as a cancer. These people will generally be very condescending and if you go commenting on a Pinch song with "where's the drop?" they WILL tell you to fuck off back to UKF.
Basically, UKF is the surface - the stuff you find there may be good, but the real gold mine is beneath.
Dude, did you hear that new Nero remix on UKF?
-Fuck no, UKF is for faggots
harry: hey did you hear that new dubstep track by funtcase?
dick: oh yea, i just heard it on UKF about an hour ago, that was a pretty filthy song.