A crooked workbench easily leads to frustration as you begin a project only to find the work surface jiggles around. Stabilising your workbench can help you to be more productive and less distracted by constant motion. Using tools you likely already have in your workshop, you can create a fix that stabilises your workbench.
Assess the source of the instability by wiggling the table. Check to see if the legs are loose and causing the instability or whether it's caused by uneven legs that make the table rock back and forth.
Hold the workbench so the uneven leg is off the floor. Measure the gap between the leg and the floor. Cut a piece of wood that's the height of this gap and at least two 2 inches wider than the bench leg. Lift up the corner with the uneven leg and slip the piece of wood underneath, which will stop the instability.
Turn the workbench over if the instability is due to loosely attached legs. Check for any loose bolts, screws or nails and reattach or tighten if necessary. If this doesn't solve the problem, create a brace to keep the leg from moving around. Cut a piece of 2-by-4 wood in the shape of a right triangle. Place the right angle of the triangle brace in the corner where the leg meets the top of the bench. Use a drill to drive a screw through the brace into the leg and the brace into the bench top.