Know you could chase down the guy who left this on your door.
It's an ad for Gold's Gym, the message being that if I signed some centuries-long contract with them, I would be able to leap tall leaflet-hander-outers in a single bound. (They don't mention whether I would also look good in one of those Gold's Gym muscle tank-tops, and by "good" I mean "as ridiculous as all the other human knots who wear them.")
Anyway, we spent some time noodling over the intent of the sentence. At first, I thought it was a truncated question:
Did you know that you could chase down the guy who left this on your door?
But on the brochure it ended with a period and not a question mark.
Then we wondered whether "know" meant "now," but that didn't make sense either.
In the end, I found my guiding light some "Simpsons" dialogue. In an old episode, shyster lawyer Lionel Hutz is struggling to stay sober. He calls his sponsor, David Crosby, who says: "Just take it one day at a time. And know that I love you."
In other words, it probably means "know THAT you could." (There's nothing wrong with dropping a "that," unless by doing so you create enough confusion that it ends up on some stranger's blog.)
Know that I could, if I wanted to, find my way through life without "The Simpsons." It would just be a lot harder.