Originally I conceived this as "Invader Zim" gag. With him gloating that nothing was going to stop him except his own incompetence. Then I realized that though Zim is stupid and vain, he is an invader and he is trying to take over the Earth.
While Gordon "ALF" Shumway is more of an annoying house guest and is a danger to no one. Except cats of course. It makes the picture less theatening to Gwen. Alf just wants to watch TV have enough food to eat.
This Gwen from the first season of Ben 10 Alien Force.