Means your plans didn't work out for some reason.
(imagine someone trying to cross one of those suspended wooden bridges and falling through)
"Dude I know you're trying to hook up with that chick tomorrow night, but if that should fall through call me up and we'll play some vidja games."
To show up; especially to a party or an event.
Guy 1: Is Lauren gonna be at the party?
Guy 2: She said she might fall through.
fails to happen
"karen's plans of becoming a grammar nazi will fall through when jon proves her wrong."
He hasn't got any money, so it looks like his plan to start a business will fall through.
He made sure to fall through with getting a party bus.
A drug dealer or hookup that is either bunk or doesn't deliver. a Fall-Through is the kind of guy that makes you wait 2 hours for a bag of weed, only to tell you he couldn't get it. A Fall-Through is the ultimate timewaster and ultimately, an asshole.
"Tony can't get weed, he's a fall-through"
"Bob said he has shrooms? 10 bucks says he's a fucking fall-through"
The sudden whole-body physical sensation of falling down or "through", as if you are sinking into a very blissful elongated state of euphoria brought on by the consumption of alcohol, drugs, weed, caffeine, and any combination.
"Man, wait. Hold on. I'm falling through!"
"Dude, I am falling through right now from drinking and smoking so much!"
"These pills are making me fall through. I feel like I'm falling!"