Aloha, Just a guess, but maybe they said スエ and not スネ? 末吉 is normally pronounced スエキチ ("uncertain luck"). Also, I doubt they would have said either スエ or スネ for 大吉（ダイキチ）, but I haven't seen the Anime you're referencing, nor do I understand much about おみくじ stuff in general, so I could be missing something.

Rikishiamaさんの意見に同感です。 そのアニメのシーンをYoutubeなどで見れたら、意味がわかるかもしれませんけど。