Lets say the Drill Sergent says something that I smile or laugh and he asks me if I think he is funny. How do I respond to that? If I say yes I will get bitched at and if I say no he will ask why did I smile and lie about it. Either way I'm going to get bitched at.

No!  What the hell is going on in this thread? Everyone is acting like your immune system somehow has an influence on whether or not gravity affects you, and that is simply not the case.  Look, gravity is one of the fundamental forces of nature. As such, nature - by default - generates the most of it... and since your immune system is a natural part of your body, it's actually a contributing factor in how fast you accelerate towards the planet.  With that said, there are two ways that you can become "immune" to falling. The first method is to hike out into the middle of a desert and start flinging yourself at the ground. Since there's very little nature in the desert, you'll be experiencing a diminished amount of gravity. (In fact, almost all of the gravity in desert climates is generated by rain forests on the opposite side of the planet.) This will allow you to learn how to dodge gravity, and eventually you'll be adept enough to avoid it in areas with a higher saturation.  The other method of developing gravity "immunity" - though again, that's not really the right word - is to remove all of the nature from your body. See, gravity requires two masses in order to have an observable result, and if you reduce the amount that you generate, you'll become less and less affected by that of other sources. While you could probably have all of your natural organs and such switched out with artificial replacements, surgery of that magnitude is pretty invasive and expensive. If you're willing to wait, a better alternative is to adopt an all-plastic diet and use the well-known property of "You Are What You Eat" to become "non-natural."  Of course, all of this assumes that you're okay with always being immune to gravity. Some people are fine with that, but others find it a little troublesome when they try to go through everyday life whilst floating a few inches off the ground. Fortunately, most cities mandate the spread of various natural substances - vomit, urine, fecal matter, and so on - on sections of the sidewalk. It's easy enough to step in some of it, at which point the soles of your shoes will once again generate gravity and you can walk around as you normally would.  TL;DR: Gravity is generated by everything in nature. Either learn to avoid it, or remove everything natural from your body. 

Depends on the DS and the moment. Later on in the cycle, they'll tell jokes a lot. Helps keep morale up after so many weeks of fuck-fuck games. I thought I'd be smoked when I laughed at  a funny comment one of my DS's made during one of our first D&C classes, but instead he just got real close to my face and whispered something about knowing the right time to laugh, and if I do it in a class he'll take it as me not taking the material seriously.

As someone who laughs at more things than the average Americlap, it was hard for me to suppress such laughter.