Noun. Used to describe the pate coloured substance found at the entrance on the anus and/or on a penis during or after anal sex with a dirty whore. The substance itself is a mixture of shit, anal lubricant & pre-cum. Rare to be seen in porno films produced today but a common sight in pioneering anal & dp porn during the 1970's and 1980's. Now days, female porn stars avoid 'duck paste syndrome' by pre-shoot enema or colic irrigation
"Yuck, that chick I just ass-fucked left duck paste all over my cock...I better get her to lick it off."