Judd Apatow and Seth Rogen have known one another a long time. They met when he’d auditioned for Freaks and Geeks in the late nineties, aka the one-season wonder that still gets cited as one of the greatest shows, and over the years have worked on a lot of comedies together from Pineapple Express to Knocked Up, Funny People and Superbad. They apparently know each other well enough for Rogen to have taken some acting advice from the director, writer and producer to heart involving, well, semen. There’s no delicate way to put that. Apparently, back in the day before Rogen, Apatow and co. knew Knocked Up would be the major hit it later became, they were trying to get through a funny scene on set. Rogen wasn’t doing his best work, and Apatow hit him with a piece of advice about masculinity and acting that’s stuck with him to this day. [This] is going to sound crude at face value, but there’s actually a lot of depth to the advice. At one time, when we were shooting ‘Knocked Up,’ we would improvise a lot, and we were improvising and Judd screamed from the other room, ‘Less semen, more emotion!’It’s been about 20 years since the two men were on set together, and 19 years since the movie hit theaters, so it’s striking that the actor really took this advice to heart. It’s certainly a memorable note to get as a young actor, and Seth Rogen told Variety it’s actually advice he’s learned to live by in his time in Hollywood. And honestly, as I’ve gone on to make films, it’s amazing how much I come back to ‘Less semen, more emotion,’ and how many times I’m writing with my friends and we’re making ourselves laugh and then we stop and go, ‘You know what? Less semen, more emotion.’ Katherine Heigl might have something to say about that joke-y advice being dispensed on what she once called a "humorless" set, but to be fair, comedy is a tricky thing. The truly great comedies always have moments that are deeply human and deeply tied to reality. The opposite of that is just joke, joke, joke, joke with no substance.Knowing when to punctuate funny scenes with emotion is a tricky thing, and it’s significantly harder to write than people give it credit for. Doubtless, he’s honed the skill through working with some greats, and kicking off his career with Apatow and then-partner Paul Feig.[It taught me] that understanding of how to balance humor and emotion and reality and comedy and how to navigate tone.I do really think knowing how to land emotional impact in the middle of keeping people in stitches is an extremely underrated skill, and the fact Rogen learned it on the fly thanks to a speech about semen explains exactly why it’s a tough realm to navigate. The good news? Knocked Up is a great example of a set that took its own advice, and ended up becoming extremely successful in the process. If you haven’t caught the great comedy movie in a while, you can give it a watch with your Netflix subscription. Just a friendly reminder when you watch that time has passed, and the baby is a full grown adult now.