Can human body release electricity?  

How could that happen. It is just unbeleivable. When you touch a empty plug point it could happen

Yes, I also had such experiences and still feel quite often. Even I feel the spark especially when I touch car handles. It is human electricity that is present in whole body but our tips constantly give out energy (bases of touch therapy) and sometimes energy may come out like this. You have constant electric current in you hair also (recall that childhood comb experiment). ECG tests done in hospitals are all based upon electricity and magnetism in human body.

What you are feeling is static electricity. When you walk around on carpet in socks or roll around in bed between your sheets and blanket, that can produce static electricity that basically builds up in your body. It is often released when you touch another person, touch a light switch, or touch something metal. It even has happened to me when I touched my DVD player. It isn't dangerous or harmful to you, it just hurts for a second. If you turn off a light in a room at night and rub your socked feet on the carpet several times and then touch like a staticy blanket or a light switch, you will actually be able to see the spark that the static electricity makes. Also, you can eat Life Savers wintergreen mints. Chew them in the dark and look in a mirror and you will see sparks flying in your mouth. I have tried it. It really works. Something about what's in the life savers grinding with your teeth when you chew them. Weird, but kinda cool.

Some times when in winter I have the same experience.I think that the reason may rest with the material that consists of our clothes.