The 2 episodes that stuck with me the most.
I was the same age range as the "Twins" when this was originally on TV and watched it all the time. The 2 episodes I'll never forget, because honestly, they kind of freaked me out (lol) were:
The one where the fathers old army buddy visits and he has a huge potty mouth and tells the boys dirty jokes, swears a lot (They had to use mild swears like "Hell" "Damn" and "Crap" since it was a family show!) he'd also use demoralizing terms against women.
So Willie, of course, being the "bad" twin, takes a liking to the guy and hero-worships him and wants to be "Just like him" so he starts SWEARING like a truck driver and being completely disrespectful to Valerie and his teachers. I think at one point he's fighting with his mom and at the height of the argument he screams (a PG-rated version of) *beep* Off!!" (Which ended up being something like "Flip off!!" or "Slag off!" or something) and I think she slapped him. It totally freaked me out because I was his age but NOBODY at that time swore or spoke like that...and then the slap. It wasn't anything I was used to so that episode disturbed me.
The other episode was the one where Willie (once again) heres that the girls in his class are all going to have a slumber party. Willie's friends start talking about "what girls do" at those things and he insinuates that they all change into there PJ's together.
So Willie and his friends all decide to sneak out and spy on the party (Mark, or course, pusses out and tells them how wrong they are) So there's Willie, peeping through the window, expecting to see some PANTIES, but instead the girls apparently started taking it ALL OFF and Willie gets and eyeful of all the naked girls!
I remember being shocked! Like "Why would all the girls get NAKED in front of each other? And What would *I* do if I ever saw THAT?
So then Willie gets caught and I remember the girl he liked screaming "Willie Hogan, you saw me NAKED???" and I couldn't imagine anything more embarrassing. Willie gets grounded for pretty much the next 30 years and has to apologize and the girl tells him it's OK because one time at the beach a wave knocked Willies bathing suit off and she never told him but she "saw everything" so now they were even.
It was another uncomfortable episode at the time because I couldn't imagine all this embarrassing nudity among my classmates going on in MY life at that age! LOLOL