Similar to 'kill it', 'get it done', or 'clutch' - it's something you say when failure is not an option, and once you proclaim you're going to smack it, everyone knows you're not fucking around.
"I don't know if we can get this edit done on time Dan"
"Nah bro lets just smack it!"
or
"Are you sure about this?"
"Yeah for sure bro we'll just smack it"
Previously thought to mean o'clockdirectly, now there are new ideas surfacing that it may well mean Acuna Matata, which we all know means Ohana, which means O'clock, which means Smack It Up.
Person:Boo hoo..im sad i lost my job/car/girlfriend/boyfriend/dog/cat/blah blah
Other Person:Well im afraid its a case of 90%Smack It Up 10%Get Over It
Another way of saying to get things done. Just do it, but so much quicker and so much better. Once you commit to smacking it, you have to follow through. "Smack it"- Do it. "Let's smack this"- Let's do this. Made famous through Casey Neistat's video, "just SMACK IT."
"Just smack it."-Dan "Let's smack this." -Dan "C'mon dude let's smack that."-Dan "Should we just smack that?"- Dan