Why can't he get it through his 'thick head' that I don't like him? [=why can't he understand that I don't like him?]
Presidential candidates are 'thick on the ground' this year. [=there are a lot of presidential candidates this year]
They were (as) 'thick as thieves' [=very close and secretive] for weeks, which made us wonder what they were doing.
(..) - Blue. Hello, Lucille. - I sent him to your house to keep you safe. - Well, he did a terrible job. Didn't he? I need someone else, someone better. What about this one? She's got thick arms. Mom, you just need to calm down a little bit. You're so tense. How am I supposed to calm down? (..)2004 TvShow: Arrested Development Title: Afternoon Delight Season: 2 Episode 6