Words U is a simple messaging app/ service which automatically transforms ordinary words and phrases to use SAT-level vocabulary, while keeping the meaning intact.
Your "hello" might become "salutations", "food" = "sustenance", "oh sure" = "indubitably", a "good time" becomes "congenial" - you get the idea. The app has a sizeable database of more than 4,000 phrases, so it's likely your texts will see some major changes.
There's maybe some comedy value in this, at least if you want to sound like Niles Crane or Russell Brand (although beware, you might get texts back saying how loquacious or bombastic you are).
But there is a more serious purpose here, too. Words U is hoping to expand your vocabulary, and as it's showing you these words in their correct context, it generally does a surprisingly good job. Anything the program highlights is displayed in blue so it's clear what's changed; tapping a word displays its definition, and if you're not happy then you can easily revert to the original text.
A fun way to expand your vocabulary.