THE GRAMMARIAN’S CONUNDRUM

I know a relative clause means
“You can’t marry your sister”
A gerund might be a female gerbil
A preposition is not as fun as a proposition
And a dangling participle could get you arrested
But above all, you do not say
I knowed my grammar
He stealed home
He catched the ball
He runned home
Then why oh why
Do you say
He flied out to center?