Try cocaine

It's a jock/PUA term. "Beast Mode" is a state of raw animalistic power, in which one excels at the competitive activity one is currently pursuing.

I am not sure of the etymology. I have located uses of the term, in it's current state, as far back as 2003, but whether it had any connection to Altered Beast or was simply an example of convergent evolution, I cannot say.

Bloody Roar had a Beast Mode too.
Rampage was played entirely in Beast Mode.

Oh yeah! I loved Bloody Roar. Probably my favorite fighter.

ooh looks like they made sequels. Turns out it's a Seattle Seahawks coined term for Marshawn Lynch. Apparently some play he made caused the people in attendance to jump in sync and created a rumbling that registered as an earthquake. So maybe my dad was right, that if everyone in China jumped at the same time a tidal wave would take out the west coast!

The Seahawks nickname has only been in use for a few years; according to Wikipedia, he was first drafted in 2007, and hired by the Seahawks (is that a real team?) in 2010, at which time the first definite usage of his kenning appears in the chronicles. Urbandictionary has entries for Beast-Mode stretching back to the spring of '03, and a large spike in activity by '06, suggesting to me that Mr Beast-Mode the football player got his nickname from a then-ascendant slang term, and not the other way around.

There was also a rap album of that name by the early 21st century warrior-poet, Juvenile, which was released in 2010, coinciding with Mr Beast-Mode's signing to the Seahawks (no, really, is that actually a team? I have never heard of them). It could be that the slang inspired the rap inspired the football player. Or perhaps the slang inspired the football player inspired the rap. Perhaps all three developed separately, or one developed separately while the other two were connected. I don't know.

Yeah even Wu Tang Clan would go "Tiger Style" or "Form like Voltron" but one was a reference to Wu Tang martial arts and the other just a clever metaphor. But those you'd hear more regularly, especially in the 1990s right when it was released. Or like everyone quoted Heisenberg, it was immediately after the knocking speech, became a meme and then went away for the most part like "all your base are belong to us."

"Beast Mode" I've been hearing a lot for probably less than a month, so an album from 5 years ago or a Playstation game nobody played wouldn't necessarily be relevant anymore, in a world where Taylor Swift is so late 2014.. especially that exact wordage.

This is where I remember "Beast Mode" from

http://youtu.be/Bbi9d-JFGx4

http://youtu.be/hihEhsdwiIk