The hole where the pee comes out on my penis is splitting upwards and getting bigger but there's no pain. maybe caused by masturbation or growing?

Could be normal.: During puberty, the urethral meatus (pee hole) changes shape as the penis grows. Before puberty, the meatus is small and round. During puberty, it elongates and may appear to be "splitting upward". If the meatus splits downward, this is called a hypospadia and can be repaired by a surgeon. If you want more specific medical advice, consider a private consult here on HealthTap.