I 'accidentaly' walked into my step-dad's bedroom one Saturday morn. I stayed with my dad on the weekends. So there I was watching him jack off.
He was naked and laying spread eagle on his bed beating his 7 1/2 in. uncut cock. It was a beautiful sight watching this handsome athletic guy work his straight as an arrow cock. I approached his bed and he got a warm solid grip on my 5 1/2 inches, uncut like him, hardon and he was masturbating me when his cock erupted 3 giant spurts of cum all over his stomach and chest and I spurt my cum on his chest also.
(I seen guys jack off spread eagle like this many, many times when I was in Bosnia with troops of other Nations, (very common) but no guy could sexually excite me like step-dad jacking off).
Dad showed me many moves on jacking but I couldn't remember them so I stay with the good old pump method. Dad and me would jack off each other mostly in the shower, in our garage and when we wrestled.