Hello! I'm new. And I have questions.

I'm one of those people that wanted to learn Japanese so that they could understand anime better. I've been casually studying the language for ~5 years now and it's just been in the last year that I've started to reliably understand spoken Japanese without looking at the subtitles. This has been really fun for me, but at times it has also caused me some confusion. It seems like I usually get confused when there's some cultural thing that doesn't translate to English very well. It seems like this forum might be helpful for that. A couple of examples:

It seems like there's some kind of cultural running gag involving ghosts and keys? Often, if a ghost appears in anime, they will briefly say "Kagi wo yokose!" For example, around the 50 second mark in this clip from One Piece: Is there a Japanese ghost story about a key or what? I've seen this in multiple anime.

Example 2: Just today I was watching Owarimonogatari and Araragi says something about "sekai gofun mae kasetsu", which gets translated as "the 5-minute hypothesis." It's somewhat self-explanatory I guess, but is anyone familiar with this concept? I want to know more.

Anyway, yoroshiku onegaishimasu and all that.

There is no relation between ghost and key.

世界五分前仮説 - Wikipedia
(I have watched the anime and googled the word as well. I'm really impressed that you are watching monogatari series, by the way. The quantity of the words they used in the anime is really huge.)

Welcome. You've come to the right place.
I haven't seen enough anime to answer your question. My first guess is that it would be a typical plot twist in general to be running around chasing after keys. I haven't heard anything about 5-minute hypothesizes. But again I'm not the best person to ask about anime.

Awesome, thanks guys. I should've known to try searching for the phrase on Japanese Wikipedia. I'm actually watching the monogatari series with subs haha. Still trying to get something out of it though. I agree, the vocabulary is pretty extensive. I basically just watch shonen without subs. It's usually pretty easy to understand.

Has Araragi got used to driving his car? I stopped watching Monogatari after he swapped from his stalwart bike to a car in Hanamonogatari. Was really disappointed.

Owarimonogatari is a story when Araragi Koyomi was a third year high school student; episodes about his past and the reason why Kiss-Shot had come to the city.

Is it? Worth watching then i guess. I'll wait until it comes out on Blu-ray and give it a try along with Tsukimonogatari.