Tilling A Bathroom I Was In The School Bathroom And I Think There Was Semen On The Sink?

I was in the school bathroom and I think there was semen on the sink? - tilling a bathroom

Recently I learned about sexually transmitted diseases and AIDS. Today when I went to the bathroom to wash my hands, I think it was semen in the sink. Brightish was yellow. Could it be just spit? It seems that the seeds for me. And I did not until I touch the sink to wash my hands and administer my face. Could a sexually transmitted disease if it sperm?