I would like to become a master at timing and interrupting people with angry poo on their way to the bathroom.

It could be something along the lines of this:
First, I will develop a firm understanding for the visual cues of impending angry poo. Quivering eye brows, sudden sweats, risky chili for lunch, and etc.

Having located my prey, I will secure the nearest washrooms with lines formed by my friends. Of course, they will have been well prepared for the task, and have been lying in wait for such a moment. They will stall the prey and leave him at a dilemma. Does he wait it out? Or does he try for a farther restroom?

Of course, eventually he must give up and aim for a farther means of relief. This is where I launch my assault. Just as he is about to leave, I surprise him and start talking. I will speak directly and rapidly, leaving no time for a retort. I can always come up with seemingly important but always useless information.

Once it looks like he’ll break for an escape anyway, I also signal my leave. This adds seconds to his overall delay. Most precious seconds. I thrust my hand out for a handshake. If I’m feeling lucky, I’ll even throw in a hand wipe before I do it. Once I have him, I grab firmly and shake.

Game Over.