My bf is having a white yellow discharge from his penis and painful urination what cous this be?

Infection: Get him checked and you could be examined to make sure the both of you do not have infections such as chlamydia or gonorrhea. Good luck. Safe sex.

Infection: Sounds like an infection, could be a STD. You both need to get checked today or tomorrow.

STD?: I suspect he has the STD called gonorrhea. He may also have chlamydia, & possibly others as well, since the presence of one STD makes it far easier to be infected by all others. Both you AND he need to be examined & treated as SOON as possible. If no other option, do go to a local STD clinic - confidential & affordable. Run, don't walk!