Never heard of them before.
Examples?
They're pretty much the exact same as Chuck Norris jokes. I first saw them on a website where you clicked a button to "generate" a Vin Diesel fact. Eventually Chuck Norris had a cameo in Dodgeball, and Conan had the whole "Walker Texas Ranger lever", so the site owner decided that Chuck Norris was a more viable name. He changed it over to Chuck Norris facts and the internet ran with it.
One Vin fact I remember: The boulder in Temple of Doom is actually made from a mold of one of Vin Diesel's testicles.