Ok, im not going to tell you what it does or do but when i was younger i use to always do it!!
hehe no you dirty minded people its not that i was even younger then that when it was my first time ohh thats sound even worst.but anwya heres goes:
1.
Go and stand under a Doorway make sure your body is positioned so it is in between the frame.
Make sure there is even amount of space between you and the door frame.
2.
Put you feet together. make sure your ankles are touching each other.
3.
Now life your arms out apart from your body and pushing againts the frame(not with palm) for about 1min.
Make sure your pushing againts it really hard,push like you have never pushed before.
4.
Now walk forward 2-3 steps with your arms in the same position as you were pushing(dont lift up your arms nore put them down)againts the door frame, as you have steped forward 2-3 steps slowly life your arms up and down?
5.
If desired repeat steps 1 to 4 again!
kewl huh? well i thought it's pretty wicked!!