Ween straddles pop and prog, adolescence and adulthood at wild Brooklyn Bowl show

The song had the same effect as the mood enhancer it was named after.

At least at first, before the death-ray guitar came in and disrupted the reverie like a knife fight breaking out during yoga class.

“Gimme that Z-O-L-O-F-T,” sang Gene Ween (Aaron Freeman), frontman for the band that bears his surname, his voice warm, soothing and relaxed, as if it was delivered from a bubble bath instead of a stage.

But then cohort Dean Ween (Mickey Melchiondo) came in and ripped this Helios Creed-worthy, space-case guitar solo that convulsed the tune into spasms of noise, a discomfiting racket whose build-up was akin to that face-melting scene at the end of “Raiders of the Lost Ark,” where something grand and beautiful turns into a nightmare and the next thing you know, you’re ankle-deep in puddles of flesh.

This, in the nuttiest of nutshells, encapsulates a Ween gig, where pretty ballads end in bloody murder, the mirthful and the maniacal become indivisible from one another and the mood swings are sudden enough to jar loose vertebrae.

This is ipecac for the straitlaced.

On Friday, the band kicked off a three-night stint at Brooklyn Bowl, amping up a packed house with a 28-song, 2½-hour set. Ween tours only sporadically since returning from a four-year hiatus last February, so shows like this have become destination events, a giddy release of pent-up demand from an evangelical fan base (How devoted is Ween’s following? After the show, Melchiondo’s handwritten set list was delivered to the merch booth and priced at $200, and those in line immediately began clamoring for it.)

A big part of the fun is that Ween have an impressive mastery of their nine studio albums (and one odds-and-ends collection) and can seemingly play any song from their deep discography at any time, so there’s no predictable structure to their shows and anything can come next.

This freewheeling spirit informs pretty much everything the band does.

After the very first song, Melchiondo was already veering from the set list, calling audibles throughout the show.

The faces Melchiondo made as he played mirrored the songs he performed: rubbery, expressive, ridiculous, pained, cartoonish, his silly-putty features as malleable as the tunes in question.

The group straddles a lot of lines: parody and homage, adolescence and adulthood, pop and prog, the sentimental and the scatological.

And so on Friday, a gentle country western swing (“Powder Blue”) breezed by faux metal rippers with unprintable song titles where Freeman screamed so hard into the mic that his face turned fire hydrant red. Schizo pop tantrums (“The Tick”) became strange bedfellows with jaunty, shoulder-rolling finger snappers with pedophile protagonists (“Mr. Richard Smoker”).

Ween can jam for days, as they did on an unabridged “Woman and Man,” or seduce with winking soft rock come-ons (See: “Your Party,” where Fishbone’s Angelo Moore joined the band on sax.)

For a group as allergic to anything straight-faced as this bunch is, they’re serious musicians, with ace accompaniment in drummer Claude Coleman Jr., bassist Dave Drewitz and keyboardist Glen McClelland, their playing fluid yet tight (an associate who was at the venue earlier in the day said the band sound-checked for four hours prior to the show).

Together, they scramble genres and brains alike.

This is a band that can somehow craft a credible tune out of its frontman adopting a Spanish accent and placing various orders for Mexican food over a beat, which they did on show closer “Pollo Asado.”

“Sometimes I lose my head,” Freeman offered by way of explanation on the Thin Lizzy-esque “Gabriel.”

If his wits were nowhere to be found on this night, it was no biggie.

He wasn’t looking for them, either way.

Read more from Jason Bracelin at reviewjournal.com. Contact him at jbracelin@reviewjournal.com and follow @JasonBracelin on Twitter.