Stupidest Brady Line Ever!
The stupidest line ever uttered by any Brady on any of the incarnations has to be the one that Greg says to Cindy when the family all arrives from the airport. I don't recall the exact words, but it was something like "You've grown up. No more pigtails," and Cindy looks at him like he's a dork and says "Greg, I haven't worn pigtails in 20 years."
If I were Barry Williams I'd be really embarrased about that line! I can't think of a more stupid line ever uttered.