What is meaning of "bad pitch" and "grab him and stuff under a mattress..." in the first episode of Rick&Morty?

I started watching Rick and Morty with English subtitles but English is not my first language, and I have a problem in understanding the exact meaning of some dialog;This Dialog is between Jerry and his wife about Beth Father:

Jerry: Whoa! What is this on the floor? Some kind of literature for a really nice-looking nursing home. Hey, honey, crazy idea bad pitch let's put your dad here. Let's put your dad in a nursing home.

Beth: I am not putting my father in a home! He just came back into my life, and you want to grab him and stuff him under a mattress like last month's Victoria's Secret?

Jerry: I told you I was ordering you something for Valentine's Day.

I have three questions about it.

  1. Jerry Says, "Crazy idea bad pitch"; I found bad pitch refers to a player's mistake in baseball, but I can't understand the reason it comes after crazy ideas. What is the relation between the "crazy idea" and "bad pitch"?
  2. In Beth's reply, She says "grab him and stuff him under a mattress," I know the general meaning of Sentences, But I can't understand the meaning of staff hear (Because in some translations, the translator translates staff as a noun! But I think the staff is not a noun (because she doesn't say grab him and his stuff ), So I believe stuff is a verb like a grab, and it refers to Beth's father. Am I correct? What is the meaning of staff in this sentence?
  3. Finally, I am not sure about "under a mattress like last month's Victoria's Secret? ". I guess Beth refers to something that happened before that she found Victoria Secret's product under a mattress, and Jerry had an excuse about it. Is my guess correct?

The "pitch" in this case has nothing to do with baseball, it's a short form of sales pitch. A sales pitch is

a line of talk that attempts to persuade someone to buy something or to take some course of action.

The 'crazy idea, bad pitch' suggests that Jerry thinks his pitch is going to be weak but he still hopes to persuade Beth to put her father in a nursing home.

The Victoria's Secret reference is, I believe, a reference to a Victoria's Secret catalogue that Jerry has been using as soft pornography and hidden under the mattress.

The "grab him and stuff him under the mattress" part means to hide him away. It has similarities to the phrase "sweep under the carpet" which means to hide something embarrassing or criminal. This phrase comes from the idea that a lazy housemaid would sweep dust and other rubbish under a loose carpet ('rug' in US English) instead of cleaning it up properly.