not sure how to define weirdest so let me pull something from my level 5 mini infodump drawer:

pachinko parlors in Japan can't cash you out, because legally speaking, they are not gambling places (and in general casino gambling is currently illegal in Japan). however, they do offer a whole bunch of prizes (just like an arcade) with a defined upper limit of 9600 Yen per prize (£46 now).

however, when there's a limitation there's always legal shenanigans -- those pachinko parlors will happily give you "special" prizes -- normally a tiiiiiny piece of gold or rare metals encased in a plastic card form, and for some reason, there will be third-party shops called "prize exchange shops" near those parlors more than glad to give you cash for those plastic cards.

but wait, we are not done here! those "prize exchange shops" would then sell these cards to ... another shop that is licensed to buy/sell second-hard merchandise, and then finally the pachinko parlors would buy those prizes again from those shops... it's a giant legal loophole

Mona (the Apple Platforms Mastodon client)

Aside from "this app have a lot of cuties inside it", I think it is feature rich (decent multi-account support, auto-drafts, schedule send, custom fonts, custom post actions and tab bars, etc etc). It also works across major Apple platforms meaning I get the same experience across my devices (the macOS App supports multi-window which fits the "go through timeline -> open a ton of posts as new windows in the background -> then deal with them one by one" workflow of mine)

Runner up is Acorn (macOS image editor), I use it to make memes and profile images -- easier to use than GIMP, pretty similar to photoshop without all of the adobe shit.

// if you ask 2005 kuriko they might have said Hamster Ball Gold and if you ask 2018 kuriko they might have said LaTeX