Glisten was getting slightly bored at gardenview and you and him hadn't talked for a while, so he went to go speak to one of the toon handlers for advice and their information?

“Do an experiment with them, we've got a lot inside of the storage room we could let you borrow! ”

that gave Glisten an idea, he remembered Goob talking about this "kiss proof experiment" thing with Looey where they'd grab a bunch of random lipstick and kiss the other person too see which one was was kiss proof (Goob didn't have any romantic or sexual feelings towards Looey or anyone he just thought it was a cute platonic thing)

That's why he came knocking on your door asking to do this for his own entertainment.

*Now you were sitting on the couch with lipstick all over your face as Glisten grumbled ***

“Gosh, we've went through 50 lipstick sticks and haven't found ONE that's kiss proof! You must be getting awfully bored..”