A glistening residue of spunk or semen which collects on the top lip of an adventurous individual post fellatio. It is not unusual for the residue to run down the sides of the mouth thus forming a striking resemblence to a glistening handlebar moustache. The word is more commonly used today to refer to the milky residue left after consuming a foamy or creamy drink like a cappucino of milkshake.
"Wipe your face dear you've got a bit of spangtash going on"
"Did you see the spangtash on her"
"I gave her a fuckin good spangtash"