A juggling pattern where one hand throws
two in one hand side by side, while the other hand throws a single ball up and down in time with one of the two balls. One of the first patterns you learn whilst
learning to juggle.
There are many variations on the basic columns pattern. Try throwing an under the arm throw over the top of the whole pattern. Or experiment with tennis and factory.
If you're a columns fan, why not experiment with other ways to use that spare ball? Simply hold the ball and move it up and down beside the two instead of throwing it. Strangely amusing...
Now move it above the two balls... move it up and down above one of them as if they're joined by a string. This is called the 'yo-yo'. Or spin it in a tight circle above the other two ('tornado'). Or even, if you're feeling ambitious, interweave it in a figure-eight between the two balls. Have fun!