That girl is so unreliable, she is as shallow as piss on concrete
Dancing with disjointed movement
At every wedding there is a guy dancing like a frog in a blender, usually the bride's father!
Not too bright and certainly not sharp!
Usefully juxtaposed to something really sharp.
The opposite of "sharp as a razor" - clearcut and incisive.
That guy is as sharp as a beach ball - he didn't even realise the girls were teasing him when they fell on the floor laughing! He was well taken in!
An able bodied driver that is in such a hurry he parks in disabled bays at the supermarket
Jerry was in a hurry to buy his beers so he pulled into the disabled space as a supermarket spastic for the night!