This is really clever! It reminds me of schemes we’ve talked about for minding backlogs where the metric is the sum of the squares of the ages (in days) of the tasks in your backlog. (Braden Shepherdson’s idea.)
My first worry with things like this is violating the QS First Principle. But that’s mitigated by the fact that you can convert triangular beeminding to the actual cumulative total after the fact. You just have to invert the formula for the nth triangular number.
So if you got x points on some day, that means you had (sqrt(8*x+1)-1)/2 drinks that day.