"I was out of line" and other phrases...

I recently saw “Cheaper by the Dozen” and it is a nice movie. It is a hilarious story of a big family and their struggle to have a better living.

Anyway, I’ve got some phrases and words from that movie which I found difficult to understand. Please help me figure them out.

1.) Charlie: What I said before—I was out of line.
Tom : Forget it.

2.) Mike : Stop calling me FedEx!

3.) Son: She started dating that doorknob.

4.) Lorraine: For the record, I am so over Nora’s hand-me-downs.

I can help you with: I was out of line meaning I was wrong to say that/do that

doorknob meaning probably somebody boring and untinteresting

hand me downs meaning things particularly clothes used by someone else and then handed on to you when they no longer need them

Fedex - sorry can’t help there