Yet another coined term meaning the contents of the testicles.
However "plaster of penis" is usually too wordy to actually thread into a sentence and so is never often used as a metaphor for come
"Fredrick the novelist was having enormous trouble including 'Plaster of Penis' into his pornographic literature, as it spoiled the rhythm of his sentence structure."
"Father MacDougall made a tissue sculpture using plaster of penis as his glue."
Semen that accidentally lands on a strand of hair, drying up and coating it, rendering it stiff.
Last night my boyfriend totally ruined my hairstyle and now big chunks are set in Plaster of Penis