IWith a name like that you were asking for it lol
In all seriousness, do yoga. I used to be as flexable as a GI Joe toy and now I'm like strech arm strong. Not only do you get to look at milf ass, you will start to loosen up after a month or so. One other thing that helps me is a stretch bar. Its a 4 foot metal bar I use to pull my arms and shoulders to a point where its slightly uncomfortable. My range of motion has improved a lot doing these 2 things over the past year.