Step 1) When explaining your motor neuron disorder to someone, be specific. Give them a bunch of details.
Step 2) Wait for that person to say something to the effect of, "Wow, that really sucks."
Step 3) Respond with "Yeah, but the worst part is it's really contagious. You should probably wash your hands soon."
Step 4) Enjoy their panicky expression for no longer than 2 seconds. One to two seconds is funny. Three or more & you're just being a dick. Don't be a dick, man. You're better than that.