Guy too skinny..?

I'm a 21 year old manly, 5'7" and 140 pounds...is that too skinny / small..?

Answers:

For your height, 140 pounds is still nourishing BUT it borders being beneath weight. If you want to look better but still inwardly the healthy band, go as much as 150 pounds. Beyond that you are already over substance.

Changing the position of penis in which it usually stays affects the sexuality or functionality?

Well, it all depends on your body type. You might only just be built like that. Everyone's different. If you aren't intake enough or you work out too much, next you may want to adjust those. Or if you're just looking to put some weight on, try working out every so commonly each week. You may not bring immediate results, but after a while you'll start to mind a difference.
If it helps you take home up your mind though, I'm a 15 guy, 5'9 and 135 pounds.
Have you tried measuring your waist near a tape measurer? I construe the average man's waistline is somewhere around 38-45, but I'm pretty much just guessing.

Kegel exercise for men?

It is a bit of the skinny side. Are you on a diet, if you are, I suggest stopping very soon. However, putting on a few more pounds wouldn't hurt.

I prefer masturbating than having sex, am i average?

umm not at all, im 5'10 and i am140 pounds.