"Betty Miller" --Huh?

The kids around the high school are graffitiing (not sure that’s a word) the halls with the words “Betty Miller”.

Can anyone provide any elucidation?

A few years back, it was “4/20” and now this new one has got the older folks a little curious.

I’ve tried the search engine and I’ve googled (that’s definitely not a word) to no avail.

help