NSFW - If you're under 18 LEAVE!
4 Girls Fingerpaint is a shock site that launched in 2006 and was based around a trailer by MFX Media (the same guys who produced 2 Girls 1 Cup).
4 Girls Fingerpaint is what most consider to be the sequel to 2 Girls 1 Cup. It is the official trailer for a "film" by MFX Media in 2008 which features four girls defecating on each other and then proceeding to smear it all over each other's bodies, hence the "fingerpaint".
There are conflicting opinions on whether or not the feces in 4 Girls Fingerpaint is in fact real. Just as is the story with 2 Girls 1 Cup (another shocking trailer from MFX Media), many suspect that it is in fact real. When the producers behind 2G1C were in court they unsuccessfully argued that it was fake. Due to the fact that they HAD in fact used actual feces in previous videos, the judge didn't buy it. So with that said, there is a 50/50 chance on whether or not the excrement seen in the 4 Girls Fingerpaint video is real.