TMZ spoke with Meth -- who didn't specify exactly who he intends to sue ... but insisted that he's not messing around.
Meth -- who continued to perform even after blood was dripping down his face -- also told us, "It's not OK ... I don't condone throwing things at the talent while they're performing."
As for why he kept going after he got hit, Meth said, "It takes a lot of heart and balls to continue performing after you've been hit in the face" and noted that continuing his show was the "right thing to do."
As we previously reported, Tila Tequila has also threatened legal action after she was nailed with some unidentified flying objects at the festival -- thrown by fans of the Insane Clown Posse -- just a couple nights earlier.