back a this
When something happened in the past.
They hit the powerball back a this.
back to back
consecutive - one after the other - successive
I had three meetings back to back
back-to-back
When you're totally surrounded by an enemy, and there's no escape, a trusted friend stands with his/her back touching yours, so you both can fight in efforts to protect each other's back. This can be done physically as well as verbally. The unity and dedication of the two coming together in this formation to act as one is a tactical defense whatever the battle may be.
At the Hot Gates (in the Hellespont), there were only two Spartans left against the Immortals who had encircled them. The two stood back-to-back defiantly in complete confidence of each other's capabilities and dared the enemy to attack, thus saving Western Civilization.
back to back
Two DJs playing together. While one DJ is spinning a record, the other one is picking a new track. As they normally store their records behind them this usually makes the DJs face backwards on each other.
DJ Tinkywinky and DJ Dipsy played back to back (b2b) last night.
back back
clear the way or get out of the way.
back back
A way of telling someone to back up, or move.
Whoa! Back back! Gimmie 50ft!
back to back
It's when you have sex with 2 separate people without a shower in between.
"Bro, how did your date go?" "So well, we hooked up and then I went over to Sasha's afterwards". "Bro, that's crazy". "You're telling me, I didn't even get time to shower in between, ran it back to back".