Fires Away At Elon Musk's Twitter

Mark Zuckerberg apparently can't wait to get into an octagon with Elon Musk to take shots at the billionaire ... he spent plenty of time Wednesday night throwing keyboard jabs at his nemesis -- as part of the rollout of his new app, Threads.

The Twitter rival made its debut right around dinner time ... and just a few minutes into its kickoff, Zuck took to the site -- which many are calling the "new Twitter" -- to go after Musk and his bird app.

First, Zuckerberg tossed shade at Twitter while explaining to Mark Cuban he hopes Threads is a more "friendly" area for people to interact.

"That's one reason why Twitter never succeeded as much as I think it should have," he wrote, "and we want to do…