When a man partakes in anal intercourse with another person, and apon withdrawing, discovers a "booger" of excrement on the end of his penis.
Hey Tom! I've still got a shit booger on the end of my cock from when I fucked your mum last night!
When a man (or a lady donning a strap-on) unknowingly hijacks a small piece of poo from anothers anal region upon removal of their pleasure tool.
Right, Matt you need to have a word with your dad because I've picked up so many shit boogers off him my penis is starting to look like a choc-chip muffin.