Seth Rogen celebrates 4/20 with James Franco on ‘SNL’

Marijuana? Check. James Franco? Check. Some cringe-worthy sophomoric phallic jokes? Check. Seth Rogen last night hosted what was probably a frat house’s favorite episode of “Saturday Night Live” from this season.

The weed humor came fast and furious (or slow and mellow), kicking off with Rogen’s monologue, during which he read from his “journal,” mentioning getting high twice before joking about setting up friend James Franco’s Instagram scandal. Franco showed up smiling, not really looking like a man hiding in shame from an underage-sex-text scandal, making the “It’s a hoax” theories seem more plausible. Rogen was also joined onstage by Zooey Deschanel and Taylor Swift (girlfriend of Ed Sheeran, the musical guest.)

Drugs returned as a theme in another “Shallon” sketch, wherein a group of idiotic schoolchildren, led by a merrily demented young girl, excitedly make plans to ruin their lives. In Saturday’s episode, Rogen played an exasperated D.A.R.E. agent unsuccessfully trying to persuade the kids not to do drugs, which they see as “kind of like a fun treat for a special occasion.”

Finally, Kyle Mooney showed yet another one of his enigmatic videos, this one called “A Very Smoky 420,” featuring a Dr. Steve Brule-type marijuana expert who makes up most of his information and doesn’t “snoke out” at all -- a bizarre, silly, surreal short, which of course is completely inappropriate for the topic at hand.

Franco showed up a second time in a short called “Monster Pals,” which had the delightful concept of monsters getting plastic surgery to look like humans. However, it was hard to tell whether it was just a whimsical idea or if there was supposed to be some sort of larger commentary about the perception that Franco is some sort of monster, or did we make him that way? Either way, it will be nice when his forthcoming film is finally out.

There were some amusing sketches that didn’t touch on Franco or pot: The cold open featured the “new face of the Republican Party,” with “Paul Ryan” and “Jeb Bush” trying to look cool, and was probably a glimpse at what political humor on “SNL” will look like for the next couple of years. “Weekend Update” featured Kenan Thompson as David Ortiz, a hungry, benevolent muppet of a man.

But two sketches at the tail end of the show caused the episode to end on a juvenile note. In “Engagement Party,” a crazy woman shows up at her cousin’s party to inadvertently out the bridegroom as possibly bisexual, talking about the time he performed a sex act on another man while he was asleep.

The sketch wasn’t executed very well, but even if it was, the idea of mocking someone’s sexual history with a forcible outing, not to mention a possible sexual assault, all seemed like the humor of school-ground teenagers from a bygone era.

Less overall disturbing but still gross was a sketch about a sperm bank that had to get rid of its inventory because it was being turned into a frozen yogurt stand. Cue lots of ejaculation jokes and jokes about mixing semen with food, which left one wondering why the topic of penises was so prevalent on the minds of the show’s writers this week. Maybe it was something they were smoking?

“SNL” is set to return live on May 3 with Andrew Garfield and Coldplay (so we can watch whether newly consciously uncoupled Chris Martin looks sad or relieved.)

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Twitter: @Zulkey