She usually 'stumbles out of bed' [=gets out of bed] around 7:00 am.
I 'stumbled across/on/upon' [='found'] this book by chance.
They 'stumbled on/upon' [='discovered'] a bizarre plot.
(..) We're close and Jo's got the VID on it. She's filming it. Suddenly, this shitty-looking green Valiant pulls up right in the way. She starts yelling and this... ...loser stumbles out of the car. He's got a bottle of Jack Daniels. He's naked. He's butt-naked. Not naked. I was not naked! (..)1996 Twister