Boy Meets World - I Thought Tapanga Was Your Sister-in-Law, Not Sister
In the episode where Cory and Tapanga get married and are on their honeymoon Eric says that he has to make it special for his sister and new brother-in-law. Now, I thought that Tapanga was his new sister-in-law and Cory his brother. Not vise-versa
That was the whole point, they purposely had Eric say that. Your acting as if this is something you discoved to be an accident in the script. Don't flatter yourself.
I don't know, it seems to me that Will (Eric) messed up the line, and the editors must have caught it at the last minute and salvaged it with a laugh track. I believe that because usually when Eric says something or does something stupid, they'll show a shot of another character doing a confused or frustrated face at him. But hey, that's just my opinion...