Masturbate to hopefully infect one of them

You begin gently caressing your nude body, while swaying your hips around hypnotically. As if pole dancing on thin air, you are an attraction hard to avert eyes from. One of the workers flubs up by pouring concrete on his shoes without even noticing.

The attention feels radiant. You can just sense their doubt beginning to set in. Are they really on the right side of this all? Time to amp up your conversion efforts. You take a few clawed fingers downtown, and start happily rubbing away while lewd-ifying your voice to its fullest extent.

Sophie: "Oahh... Unh... Gawd, this is so GOOD...! (Don't you wanna be like me?)"

Worker 1: "Aah... I-"

The other guy nudges his companion with their elbow.

Worker 2: "(C'mon man snap outta it. We gotta look cool in fronta the freaks.)"

Sophie: "Aww yeah, I'm a real freak. I bet you handsome guys wanna freak me a bit, huh? Don'cha wanna freak me? All. Night. Long..."

At this point, you 'slip up' and smoothly tug yourself over the threshold of orgasm.

Worker 1: "H-huh? What... what's happening?"

A sly smirk develops on your face, as you watch the two poor saps falling helplessly under the contagion. The change happens in the exact sequence as yours: At first there's the tail. Then the ears. Then fur, facial features, elongated midfeet, then the muscle. You're already a fitness model on all kinds of steroids, but guys under this transformation could probably tear a fire hydrant from the street. Guess it helps that they were physical labourers to begin with.

While confused at first, the two catboys soon find the reins on their turbocharged bodies, and begin to undress one another.