Weight gain

I am 6 foot and weigh 150 pounds and eat like a pig but never gain weight how can I put on some pounds

Being that muscle weighs more than fat start putting on muscle (naturally).

I like push-up and pull-ups.

Start the following workout if you're healthy and physically able and you may want to consult your physician.
When you are sitting around watching T.V. use this time to workout.
20 push-ups, rest 2-3 minutes, 20 more.... do this 15 times. There is no rush so if towards set 10 or 12 you need to take an extra 5 minutes between sets go ahead. ....but finish!! If you can't do 20 push-ups comfortably find the amount of reps you can do comfortably 15 times Try and do this everyday!! You won't believe what will hapen because you will soon be able to do more reps. Once you get a little stronger, add sets like an extra 10. Now you are up to 25 sets of 20 push-ups..everyday. Pull-ups are the same but you have to start with way smaller reps. I am jumping way ahead but you will eventually really add major strength by adding weight on your shoulders and lowering your sets. But just start with the first part of this........Remember nothing is easy but set goals for yourself. This will be great for you..no money,no trainer,no gym expense, at YOUR own time and you can start right now....Remember, if not every day try for every other day for push-ups. Hope this helps.. Try also and eat right, go to a health food store or maybe some specialist in diet can help you.
Familycoach

Muscle weighs more than fat. Have you tried building your muscle up and not concentrating so hard on all the food you eat? Or this could just be your body type and it might be hard for someone like you to gain some extra weight.

eat lots more chocolate and drink lots more whole milk..these will slow down your metabolism and make you stack on the weight
make sure you are snacking on pizza, pies,party rolls and chips.Eat more at dinner and into the night just before bed

Some people just have high metabolisms. I hovered around 145 pounds for a long time but then I got older and my weight took off and now I'm 184, even though I ate the same