It's a way to pour a mixer with a little more punch. Pour your normal alcoholic spirit into a glass, fill it with a soda of your choice and before serving gently pour another shot of spirit in a circular motion on top.
Oldmate takes a sip of a drink he's just been served "geez mate this has a bit of a kick to it!"

Server replies " you wanted something with a bit of a sting mate so the backhander you got"
by Team Jelly June 19, 2022
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The act of shitting on the back of your hand and slapping someone across the face.
Bro 1: My girl has been cheating on me with some hockey player. Bro 2: don’t sweat it dude, he’s got a Baton Rouge backhand headed his way.
by Frunkle December 4, 2020
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