Is it safe to swallow cum?

There is no great answer for this one... Eating your own semen is perfectly safe; you may or may not like it because of the salty taste. Eating semen from a partner or friend may not be safe because of sexually transmitted diseases, including AIDS, Herpes, and Chlamydia etc that can be carried in semen — so it's wise to stay away from other people’s ejaculate unless you know they are disease free.