In the part where the police shows Anderson a picture of Beavis and Butt-Head, he says they look like ones who were "whackin off" in his camper. However, in the beginning when Beavis and Butt-Head first goes to see him, Beavis says he didn't know Anderson had a camper. Was this an error in the movie or Beavis is really THAT stupid?
This is so simple... Beavis says he didn't know Anderson had a camper, then he and Butthead go into the camper to watch t.v. Anderson says 'they look like the kids who were whackin' off in his camper' because he saw them leave the camper and assumed that was what they were doing in there, since that's what they do whenever they go into his toolshed. It's not a plot error, and Beavis really didn't know Anderson had a camper.
Have I licked his rectum? No! But there was this one time when Butthead and I were playing truth or dare...
I don't know about that. Anderson's wife told him what they've come to do (fix the TV), so I don't see why he would still assume they were whacking off.
Because he knows they were'nt there to fix the tv, because as he says 'the t.v aint broken'. Beavis and Butthead broke the t.v. while they were in the camper, which also leads Anderson to believe they were 'whackin' off', because 'boy, you never seen two kids do so much damage whackin'. They're like a couple of dang spider monkeys...'