"Gas it!" What does it mean?

I was watching ALF series and came across a phrase I cannot completely understand.

The scene is at an animal shelter. A little girl comes inside to pick a pet. The girl seems to be bitchy and bossy, telling everyone what to do.

She sees ALF and asks, "What is that monstrosity?" (you know, ALF doesn't look too cute and cuddly)

"That's a dog, I think," answers the shelter emplyee.

"Well, gas it. No one's gonna want it," says the girl.

Urban Dictionary says "gas" means "exaggerate" or "tell lies".
Does the girl mean "Come on, I don't believe you, this is NOT a dog!"?

I switched to the Russian voiceover to hear how they handled that part... Haha, they just skipped it! The translation just goes: "No one will want it." So I guess the translators also had difficulty with it.