Slightly Funny:
* Vexes: This one works grammatically but is a bit dry.
* Sexes: (Not recommended for polite company!)
More Playful:
* Tex-Mex: This is a play on words that works because it is a common phrase associated with Texas.
* Tex-Mexes: This is a silly plural form of "Tex-Mex."
Let's Get Creative:
* Hexes: Imagine a mischievous witch putting a hex on the state of Texas.
Ultimately, the funniest rhyme depends on your audience and what you find humorous.