When two makes, usually grossly overweight, cover themselves in pig slop and run into each other repeatedly. Often headbutts will occur as an indication of love.
Once a year, my good friends Alfredo and Scott meet up and start slopping.
having a girl suck your dick, and as you come, shove your cock as far in as you can, resulting in her making her vomit.With your cock in her mouth, she will have a mouth full of puke, cock and come, hence the slop on your pig.
The inadvertent, surreptitious, and often accidental placement of one's genitalia on another's person, usually the face or head.
"When you have a small dog that sometimes cuddles with you in bed, if you close your eyes for too long, you have to get used to the occasional dink across the forehead. You get used to such junk-slopping."