Is it normal that our two year old gets an erection every time he sits down to poop?

Me and my SO noticed this as we started potty training our two year old.Whenever he's sitting and he starts to poop he gets a full on saluting erection and sometimes it even bobs up and down seemingly of its own accord as he's going.It's not worrying per se, except that if he does pee he ends up overshooting the toilet by a long shot.It's just... Peculiar.So I was wondering has anyone else experienced this with their kids. via /r/Parenting http://ift.tt/2n7hGeE