when something is so rad that it scares the shit of you.
"...so it turns out that the spooky dude who lives down the street isn't retarded, he's just a recluse and he saved a little girl's life the other night."
"are you serious?"
"yeah man. and he used to be in a gang."
"shit, that's boo radley."
A fictional significant other. That is, a boyfriend/girlfriend/spouse, one that a friend frequently refers to, that neither you nor any of your friends has met. Refers to the slang boo as a sig. other, and, obviously, a reference to the secretive, mostly-hidden character in the novel, To Kill a Mockingbird.
"I should bring my girlfriend out from New Jersey for prom..."
"Oh, the internet one no one has ever met? Your Boo Radley?"
A alcoholic beverage consisting of a small cup full of ice, 3-4 shots of your liqour of choice (original liquor used 'Spiced Rum'), and a drop of coke (or other pop). If there's more than an ounce of coke mixed its called a "big icy"
The next day was a write-off after drinking boo radleys all night