A series of mix CDs by Anabolic Frolic out on the Moonshine Music label.
There are 6 albums in the series, each one consisting of 15 very, very, happy hardcore songs, mixed continuously. The series is very popular in North America; at least some of the 6 albums can usually be found in a given major record store where I live, although as time goes on earlier releases have become more difficult to locate.
The first CD is simply titled "Happy 2b Hardcore". Subsequent discs have a "Chapter X" suffix where X is 2 - 6; #6 was recently released and claims to be "the final chapter". Cover art invariably features tiled happy faces hovering over a background of speaker cones in cheap 3D, all in a variety of ugly colours: yellow for chapter 1, then red, blue, green, purple, and black for chapters 2-6 respectively.
If you like happy hardcore, they are The Shit. If you don't, it goes without saying that they are Shit.