The ability to determine what decade a clip of porn is from merely by observing Ron Jeremy's appearance and other 'hairstyle' attributes.
Dude ) Hey Phil! Come and check this clip out!
Phil ) Hmmm. Ron Jeremy
is skinny, and the hairstyles are 'un-trimmed'. This is classic 80's porn
Dude ) You sir are correct! Excellent Paleo-pornography skills.