KEEP THE FAITH: On the last night of a big rock tour, anything can happen--especially when the rock tour's headliner is a merry prankster like Billy Idol. When his opening act, Faith No More, arrived in its dressing room before the tour's final concert in Seattle the other night, the band was greeted by a gaggle of livestock, including two pigs, a goat and a bale of hay. Later during Faith No More's show, Idol dumped two vats of dead smelts over the group's heads. FNM took revenge during Idol's show, running out onstage and cavorting about--buck naked--during Idol's rendition of "Got to Be a Lover." . . . Tired of those smoochy nighttime dedications you hear on most rock radio stations? Tune in KROQ-FM's the Poorman, who recently debuted a Monday night "Anti-Dedication Hour" where listeners get to dedicate songs to people they hate. "The phones absolutely blaze whenever we do it," says the veteran KROQ deejay. "It's a great antidote to all the love-song mush you hear everywhere else. When it comes to love, there are probably more people who've been burned than can offer a success story." The best part of the feature is hearing KROQ listeners' imaginative (not to mention vengeful) song selections. They've included: "Ugly" by Fishbone, "Head Like a Hole" by Nine Inch Nails, "Taste the Pain" by the Red Hot Chili Peppers, "Idiot's Rule" by Jane's Addiction, "Unhappy Birthday" by Morrissey, "Lie to Me" by Depeche Mode and--our fave--"Big Mouth Strikes Again" by the Smiths.