To get absolutely out of control drunk as hell. People that are in the presence of someone raring up should either choose to rare up also or stand the fuck back because you may get hit with anything in sight. Fist pumping may be involved.
You gonna get rared up tonight shit stain?

Let's get rared up!

Get rared up or fuck you!

I was so rared up last night.
by R Tayla August 4, 2010
To square up to someone in order to incite a violent reaction. To let someone know that you won't take shit from them, and you are willing to throw down if necessary.
"Some guy rared up to me, so I knocked him out cold."

"This guy was getting mouthy, so I was gonna rare up to him until my friend stopped me."
by Nick Fletcher January 31, 2007