To be like a bull in a china shop is a simile used to describe an extremely rough or dangerous person in a place where gentleness is a must.
It brings to mind the image of a huge rodeobull exploding into a tiny curio store and throwing his weight around in a beserk rage, annihilating every last teacup.
The huge wrestler burst into the house, knocking pictures off the wall like a bull in a china shop.
a twist on the old idiom to describe yourself or someone with a large penis. It is hyperbole in most respects but also speaks for the extreme close quarters that one encounters in some china shops. It could also be used sarcastically if someone is known to have a penis of below the average size.
Jim- "Hey Jane i saw your boyfriends wang in the shower at the gym last week, im not surprised that he's been a little shy in the bedroom."
Jane- "Do you mean its small or something?"
Jim- "Lets just say he wouldnt have a problem having a boner in a china shop."