As Paul Thomas Anderson has often said, seeing Dirk Diggler's gigantic penis in Boogie Nights is like seeing the shark in Jaws: It's more powerful if you have to wait for it. Now, thanks to Grantland's 16,000-word oral history of Boogie Nights, we know exactly how they made the pivotal prosthetic. The model itself was made of plaster, with a little public merkin specially made to match Mark Wahlberg's hair color. (The team also created a special bulge for his pants, "a woman's stocking knee filled with birdseed.") After the team tested some prototypes, the final penis ended up being a little smaller than Diggler's oft-mentioned 13 inches: "We sculpted a version that was 12 inches long, and we tested it, and it was just way too big," special-makeup-effects coordinator Howard Berger told Grantland. "It looked like a weird monster penis." The version seen at the end of the film was seven slightly tumescent inches: in the words of editor Dylan Tichenor, "It was the size of John Holmes' penis, but Mark is like eight or nine inches shorter than John Holmes." Standing up, he means.
To get honest reactions from the rest of the cast, Wahlberg wore the prosthetic even when it wasn't needed onscreen, and everyone involved still has high praise for his performance. "What Mark Wahlberg did in that movie was all sorts of things that he had to absolutely commit to," said director of photography Robert Elswit. "He had to put a prosthetic cock on his own cock, you know what I mean? That's asking an awful lot of an actor, honestly."