There's this place I sometimes go for lunch that has a loyalty scheme. Every time you get something to eat, they'll stamp your card and when you get enough stamps, you get a free meal.
Of course, this being 2019 and all, this stamp has to be virtual, cause shit, why not!
This place chose an app that's hilarious. First of all, it hasn't been updated for iPhone X, so it looks awful. Second of all, you need to give your phone to the waiter so they can add a stamp and confirm it by submitting their restaurant secret password code (I do hope it changes frequently!).
And last but definitely not fucking least, to put the code in, you have to use a virtual keyboard. Of their design. That's extremely non-deterministic.