Do you guys ever hear て+よ? Maybe it's somewhere else on the website, or simply slang, but I wanted to get some more expert info. For example, I interpret that「冗談しないでよ」expresses "Don't kid/joke around" but is the よ more of an exclamation point, or something else? I'll look for some more examples...

I've heard it, I think always as ‾ないでよ （それしないでよ etc), so I think yes it's using よ in the same way it's being used here, as an emphatic. It's definitely more slang-y than the above pattern, but it does get used sometimes, in my experience mostly in a whining tone of voice ;-)