GOOD MORNING ERECTION OF MEN.

It is physiologically impossible to pee while AROUSED as your urethra is a one way street -ejaculate or urine - else infection and damage to reproductive systems ensue.  Nature has taken care of this.  Morning erections is NOT arousal - your subconscious has caused your erection as a last resort to STOP you pissing your bed!       

Your subconscious knows it will be PHYSICALLY IMPOSSIBLE to urinate with a FULL erection (if you function properly) That is why you NEED to pee, that is why you feel your bladder is going to explode, that is why you can't pee straight, that is why you can't pee straight away with the erection because you literally have to convince your subconscious that you are not aroused and that you need to pee. You then can pee - even when erect.