I can tell by the shape of your head
When someone looks at your head and immediately thinks your life is a joke. It's like they're saying your brain is a disaster and your future is a punchline.
'I can tell by the shape of your head you're gonna end up in a dumpster.'
'Your head is too round. You're gonna be a sponge.'
'You've got the head of someone who never had a job.'