EVERETT, WA--In an attack denounced by Crestwood Elementary School teachers as "shameful" and "thoroughly uncalled-for," educational puppet Donny Dungarees was pelted with crayons during a fourth-grade assembly Monday.       Dungarees, a 26-inch-tall felt puppet with orange yarn-hair, sustained minor injuries in the attack, including a torn plaid kerchief and crayon marks to the face and neck. Dungarees' puppet pals Peggy Pipecleaners and Friendly Policeman Henry were unharmed.       Three 10-year-olds were held for questioning in connection with the brutal puppet-pelting, which occurred during the presentation of "It's Okay To Say, 'No Way!'" The anti-drug play was performed at 10 a.m. in the multi-purpose room by The Wondermakers, a three-member Everett-area puppetry troupe committed to spreading positive messages of self-esteem and good behavior among youngsters.       "When I walked in, it was like a riot had broken out," Crestwood vice-principal Warren Knauf said. "Children were shouting, the learning corner was littered with broken crayons, and crushed milk containers were flying through the air. Coach Cranmer had to be called in from the gymnasium to blow his whistle to restore order."       Though the exact cause of the outburst is not known, some authorities suspect that noted problem students Tim Messman, Kevin Isbister and Nicky Brazeau may have instigated the incident. According to teacher Georgia Sluman, the three boys began exhibiting inappropriate behavior shortly after Dungarees and his companions took the stage.       "As soon as those puppets came out of the trunk, they started to snicker and whisper," Sluman said of the trio, who last week were caught plundering the Castaway Book Club's treasure chest of prizes. "From my vantage point, it definitely looked like they were being disrespectful to our guests. Whatever they were saying, they most certainly did not have their listening ears on."       Approximately 10 minutes into the performance, just moments after Pipecleaners told Dungarees she was considering trying drugs to be more popular with the other kids, the barrage of crayons began.       Friendly Policeman Henry initially tried to defuse the situation by waving his hands and saying, "Some of our new friends aren't paying attention, Donny." But despite such efforts, the assault only escalated, as the airborne crayons were followed by erasers, fruit rinds and several pencils. A majority of the projectiles struck the puppets' hard plastic eyes or rebounded off their soft velour torsos, whipping the crowd of fourth-graders into a frenzy.       The incident was not the first to mar a special assembly at Crestwood Elementary. In October 1997, a performance by the instrumental group Eight Autoharps & A Guiro was twice interrupted by cries of "Boring!" from the back of the auditorium. This past March, a man dressed as Freddie The Fire Safety Frog was shoved from behind by a third-grader invited onstage to participate in a "Stop, Drop & Roll" demonstration.       School principal Stanley Rumsell has vowed to get to the bottom of Monday's crayon-throwing incident.       "The Wondermakers were guests at our school," said Rumsell in a 3 p.m. address delivered to the entire fourth grade before they were allowed to line up for the buses. "Do we want visitors to go away thinking that students at Crestwood are not grown-up enough to sit quietly and listen? Maybe we should just sit at our desks all day long instead of getting to enjoy fun new activities."       Rumsell has urged those responsible for the attack to step forward. If no admission of guilt is made, he warned that all fourth-graders will be kept inside during lunch recess for the next month, making everyone suffer for the inappropriate behavior of just a handful of disrespectful students. Rumsell said fourth-graders can thank their misbehaving classmates, not him, if such a punishment is handed down.