i dont believe daxter has ever passed gas on the screen... off-screen, possibly. if he has on-screen, poor jak! maybe daxter will fart if you have jak stand still for long enough.
Why should he not be able to.
Of corse it's not a important part of the storyline. How manny days/weeks passes during a game, and how manny times do you ever see they eat or take a shit during the game?
Realy few times eating, and never going to the toilet...