If you like to stick to your man and hunt the body, which means level changing and making him turn when he gets set, work the lateral jab by doing short, quick drag steps to the right as you pump a sneaky jab.
There is not much power here and I like it mainly as a nose shot to set up power shots and as a chest jab to fix his hips and move around him with hooks.
You must have your rear hand guard high on the head and/or have good head movement otherwise you will run into a hook.
Try drilling this by jabbing quickly back and forth in ones, twos and threes, mixing up direction to right and left to condition your hips for lateral movement. This is all about setting up pass hooks, uppercuts and the cross. As with much of your boxing what you are trying to do here is get to his shoulder and hip, two feet on one, two hands on one, and then mug him before he adjusts. The specific aspect of the sneaky lateral jab is splitting us hands. You are moving to the side so that you can pump your hand between his gloves as you get off line.
The foot that goes flat depends on what power punch you want to set up. Boxing is largely the art of shifting weight from side to side. If you want to throw a right, then do your slide jab with a flat right foot and coiled left foot. If you want to jab and hook, coil the stepping right foot and drag the dead left foot flat so it can be engaged as an accelerator.
As a meditation on this just stand in front of the mirror and hook and cross, pivoting with the foot under the throwing hand and shifting your weight back and forth across the body with opposing pivots. Now do it on the bag. Do this in the doorway at home with your open hands, hooking the opposing doorframes as you pivot.
One of the reasons to master this is so that you can learn to post it, and crush his ass coming in. The posted jab is up next.