Second Hand Semen 

The residual effects of a blowjob still remaining upon a womans lips in the immediate hours after said blowjob.

So your friend got a blowjob on the way to meet you, and you know this. And when she goes to kiss you on the cheek after dinner you step back quickly because you dont want any of your friends second hand semen from her lips, and or mouth to reach any portion of your skin.

This happens to Larry David in season 7, episode 2 of Curb Your Enthusiasm.

Second Hand Semen by RNail June 3, 2010

Secondhand Semen 

The transfer of genetic material through semen that the uninvolved party receives when sharing beverages or Chapstick with someone who has recently participated in oral sex.

"Can I try your smoothie?"
"Sure, if you want some secondhand semen..."

Secondhand Semen by Puckslut1223 March 24, 2013