When i was 18 I was taking yoga and tai chi classes in the evening after school. That got me in incredible flexible shape. One night in bed and bored and horny, I decided to toss my legs back up over my head and see if i could get my cock near my mouth. To my surprise I could get a little bit past the head in my mouth.
I worked more on the flexibility and eventually could get half my cock into my mouth! It started out as an erotic alternative to jerking off at night but the more I did it, I was enjoying the pleasure more so of sucking versus getting sucked.
I was pretty much able to keep doing this into my late 20s, but as the years went by I lost the flexibility. But over the course of those years I self drained my balls so many night. I can't even imagine the quantity of cum I consumed being able to blow myself!