maple classic™ 
page 15 of the SIGBOVIK 2017 proceedings
http://sigbovik.org/2017/proceedings.pdf
"Towards A Well-Defined and Secure Flirtation Protocol"
i think mastodon could learn from this
(also just in general check out sigbovik because it's hilarious http://sigbovik.org)
(by the way i am not serious about learning anything from any paper published at sigbovik)
(but it's funny as hell and you should read it)