Play nonstop for a long time. Do tdm, submachine guns or short range assault rifles. sounds like crap but works for me.
CoD MW2 Because L4D2 is WAY too repetitive and you may get bored fast While CoD is Action packed and Great online. Spec Ops is another great thing in MW2.
Hacking or killing
you should do all the easy challenges you could do
man ... in cod4, infinity ward didn't focus on offline multiplayer so you cant level up but in cod mw2 this problem is over ... GHOST out . (overlord mw2) EDIT BY SOMEONE ELSE: The only way you can is to hack or mod, I dont know how so get black ops when its out or get MW2
it is probably better than call of duty waw or cod 4 but not mw2
Just gain weight.
CoD MW2 Way better graphics and extremely well thought perks.
Neither have came out yet so it's hard to say. Bf3 has way better graphics and will be more balanced than Mw2. Mw2 will have the same graphics and not much has been improved much since mw3. If you disliked mw3 you will hate mw2. Mw2 will run on 90 frames per second and bf will still be at 25 frames per second on console, 30 on pcds. In my opinion, I really do not know which one will be better. Mw2 seems to have more bad things about it so you would think bf3 would be better but cod is cod and the overall feel to it is better than bf and that's what makes it hard to decide. If you have always been more of a bf fan get bf3. If you have always been more of a cod fan get mw2. If you like both get both! I will be getting both this fall because I like both.
The fastest way to gain muscle and lose weight, would to be running daily, aproximately 3 miles, and doing a simple ab workout, such as 20 pushups, 50 situps, and weight lifting for about 30 minutes everyday.
Surgery or fasting is the fastest way. Of course getting slim fast is the best way to gain fat even faster. If you don't change your eating habits and lifestyle, you will continue to gain weight following your quick fix. Perhaps, you could go back and get different ancestors with slim genes.
The usual way to do it would be to take them on rides, but training all day until they are at 20% energy is the fastest way.
Black ops hopefully will be a improved version of COD MW2! The BETA should be coming out soon so I would really recommend downloading that! Put in your input about what you like about it at Treyarch . That way they can improve it so its 100 times better then Modern Warefare2! That's what we all want.