Jacking off isn't really a hobby unless you're serious about it. For example, I like to live dangerously, so I've jacked off in all sorts of places where it is not the best solution to pass the time. In a ditch? Jacked off. In a combat vehicle? Jacked off. But my favorite challenge is the porta john challenge. What you do is go to a training area with blistering heat, make sure you consume lots of caffeinated drinks, against all known advice and directions by your superiors. Once there, break out the ol' phone and start looking at your favorite porn and start jacking off inside the porta john. If you manage to finish before you pass out, you win, and if you don't, then you're probably going to die with your dick in your hand. Bonus points for your corpse being found with the most disturbing porn ever. Also, your battery will severely degrade from such usage, so make sure you budget for a new phone.