Here:

MedlinePlus Medical Encyclopedia: Blood in the semen

Pay particular attention to the part where it recommends you call a doctor. Probably nothing to worry about, but it's worth checking.
birdgirl73 Reviewed by birdgirl73 on . bloody cum Fucking son of a bitch, during a little sexual activity today, I found that my cum was a pinkish color - of what I presume to be blood. Is this anything serious? Has anyone else had this? Everything else is fine. I feel fine and it's all working good. Just a pinkish color to the cum, that's all. PS. No, I don't fool around. I'm in a committed relationship and both of us are STD free! Rating: 5