The thick and almost malleable combination of phlegm from the mucus membrane in your throat and thick, usually potent, semen. Usually found at the crime scene or a rape victim, or the bedroom of a housewife trying to rekindle her love with her husband of 20 years, but couldn't stand the taste of her mate's sperm and spat it back out, half-way through swallowing.
Similar (sexual) terms include Casper's Tears, Spit Dicker, White Wedding, Tapioh-no!, and Toothpaste Gag.
Officer: Well, looks like this was an oral sex rape case, sir!
Lieutenant: Really, Officer? What makes you say that?
Officer: See that, sir? *points to a clump of white goo on the pillow, next to drips of blood* That, sir, is pure bona-fide phlerm.
Lieutenant: What's phlerm?
Officer: Look it up on Urban Dictionary. It ain't pretty. God help the victim...