Personal favorite is twat waffle
They couldn’t pour water out of a boot if the instructions were on the heel
We have a similar one to this when someone is incompetent which is “They couldn’t organise a pissup in a brewery”.
“Are you a professional moron, or just a gifted amateur?” - Carl Johnson, GTA: San Andreas. Top tier.
I never understood if that was directed at the car I just crashed into, or me (as the pilot)
“Wow, you’re the worst part of both your parents”
Please apologize to the tree that produced the oxygen you breathe.
“Wisdom pursues you, but you’ve managed to outrun it.”
or
“Wow, it must have taken all three of your brain cells to come up with that.”