Pee-wee viewers of Disney’s box office-busting critical darling Zootopia will get plenty of the punchlines in the anthropomorphized crime caper, but there’s one gag that will sail right over their heads for being too blue — literally.

SPOILERS FOLLOW!

As bunny cop Judy Hopps (Ginnifer Goodwin) and her partner in crime-solving Nick Wilde (Jason Bateman) track a missing-persons investigation, the case eventually leads the pair to an underground flower-harvesting operation whereby a ram in a yellow jumpsuit works meticulously to cook up a volatile blue serum that turns animals wild.

Sound (vaguely) familiar? The visual homage to AMC’s seminal meth-cooking drama Breaking Bad goes from suggested to certifiable when viewers learn that the names of the serum’s manufacturers are Jesse and Woolter. No, that’s not a typo.

“At a certain point, the scene just wanted to be that scene, so we said, screw it, we’re just going to name these two characters Woolter and Jesse. Not Walter, but Woolter. For a ram,” laughs co-director Byron Howard. “That one made lots of people at the studio groan.” For a film loaded with zoologic puns, such a reaction says a lot, as co-director Rich Moore adds, “That one almost broke it. That was bending a pun to its limit.”

As Howard and Moore tell it, the Breaking Bad tribute came about by the accidental manifestation of years of using the show as an example to describe the climactic scene.

“It was just one of those things where, when we would talk about them finding the nighthowler flowers being distilled into a serum, we would just kind of add to the end of it, ‘Like Breaking Bad,” Moore says with a hearty laugh. “We’d say, ‘A lab…like Breaking Bad’ or ‘Blue flowers, like Breaking Bad.’ And little by little, it just became like Breaking Bad.”

The gag works. During copious test screenings, Moore and Howard say they can consistently count on hearing adults crack up at the reference, coursing through the audience like a ripple the kids never notice.

The duo continues, “We kept thinking, well, at some point we’ve got to pull this back, but as we kept building the scene and designing it, we kept saying, well, there’s nothing really offensive about this. It’s a ram growing flowers in an abandoned train car, making a chemical serum. It evokes a show from pop culture, but it’s not like it’s something that’s offensive to the audience. But it really puts you into that mindset.”