Does anyone remember a movie from the 80s about kids building a spaceship?

I have been casually searching for this movie for a while. I remember watching this film as a kid…. it was probably from the mid-80s. Kids build this spaceship, I think out of stuff they find in a junkyard. They go to this other planet where this alien does a comedy routine. I remember the alien quoting TV commercials from earth saying “germs, germs that can cause bad breath, diariahh” Does anyone remember the name of this movie?

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