jackassume
When you guess something so dumb it makes your brain scream. Like you're a idiot who thinks they're a genius.
He jackassume’d that the teacher would let him leave early. She didn’t. He screamed in agony.
She said the dog would eat the homework. It didn’t. She jackassume’d and cried.
He thought he could win the race without training. He jackassume’d and got last.