Pushing Thread

the need to drop a "deuce" so badly that that it is sticking out and touching the thread of one's undergarment.

Hey Phil, where's the shitter,? I'm pushing thread.

pushing the green thread

a colloquialism used in phased array ultrasonic testing describing the act of maximizing the signal amplitude over a range of angles during calibration

Yo, did you push the green thread? Your sensitivity is whack at 60°
Took me forever to push the green thread on this notch. Sigh.
What’s the point of pushing the green thread for an ‘S’?