* CrossesTheLineTwice - One episode did this with a joke where Ben puts David's goldfish into a food mixer (since they don't have a tank for it yet) and then accidentally switches on the mixer. At the end of the episode, the show broke the fourth wall with actor Gary Olsen explaining how they used a prop fish - and then went into this trope, with another scene where Olsen accidentally microwaves the real fish.
* SomeAnvilsNeedToBeDropped - One of the Christmas specials ended with Bill giving a speech about how easy it is to become homeless. This was about as far as possible from subtlety, but nevertheless an important message, especially given the time of year.