Context would help - but I think this is two idioms together: #1: There is an English idiom "everything but the kitchen sink." You use it when you want to say a great many items. Example: "In her suitcases, she packed everything but the kitchen sink." means: she brought a lot of luggage and bags with her. #2: "throw in" means to add to something. Examples: "I'd like to buy a notebook. And throw in a couple of pens, too." or "When you make this soup, you can throw in some tomatoes for extra flavor." So without context, I would guess that "throw the kitchen sink in" would mean that the person is asking for *everything*.

"Throw the kitchen sink at them" is a sports term used in football, baseball, cricket and rugby. It means doing all you can to fight and win, specifically when a batsman is about to hit the ball. I have seen this term used in Irish and American newspapers. Hope this helps

It means include everything possible. The usual expression is, 'everything and the kitchen sink'.

Oh OK that’s what you’re talking about LOL. So throw in the kitchen sink needs to throw and everything is part of the deal, That is to say I’ll give you everything you possibly could one if only you will give me this one thing of yours. I will even throw in the kitchen thing just to be nice ha ha