When you are the sixth person to have unprotected sex with a woman in the last 12 hours.
I hooked up with Jasmine at the party last night, apparently I got slimey sixths but man, she was too hot to pass up.
When you're the second, or later person to have either protected, or unprotected intercourse with a lady in the last 12 hours or so.
Different from sloppy seconds because it implies the last guy(s) used a condom or did not cum inside.
Last night Robbie hooked up with a party slut. He had no idea he was getting second hand pussy though, and just assumed that was her usual tightness.