[King there is suddenly a very big lecture Ian needs to give you.
It's not Ucchii's fault that he doesn't know about modern developments, so Ian just sighs and puts his tea down to slide his wallet out of his pocket. From there, bam, have a condom thrown at you Ucchii. Seriously, King...]
They're tubes of latex that prevent your partner from coming in contact with your body fluids. They help lower the risk of infections and the potential transmission of any underlying diseases your partner might have. And... not that it matters any for either of you two, but they're also a useful method of birth control.