“turnt” and “turnt up”
Solution 1:
According Green’s Dictionary of Slang the expression is relatively recent:
Turnt adj.:
(US) subject to intensified emotions, under the influence of drink or drugs.
- 2005 Urban Dict. 2 Aug. [Internet] Damn, I am all turnt on! or I am getting Turnt to night at the club!
Also
turnt (up) (adj.):
suffering the after-effects of a wild party.
drunk.
The following website explains how the term turnt developped:
The word has been all over social media, taking over every other word in rap songs and hip hop music, and creeping its way into the lexicon of youths everywhere as they scream it at parties, on the weekends, and even at school: "turnt."
As it turns out, the word "turnt" is the third generation kin of two other words.
It all started with the word "turn," as it means "to change in nature, state, or form." Then, with the recent addition of "up" at the end of "turn," the phrase came to be a verb signifying passionate, deliberate, and excessive partying or celebration. For one to "turn up," one must actively decide to transcend the mundane of every day routine and single-handedly change the course of the day to be full of an all-encompassing enthusiasm.
Then, from "turn-up" comes "turnt" which is what you name the ultimate state of nirvana or success achieved by the aforementioned partying or celebration. You turn up to get turnt and there's no in-between.
(Bustle.com)
In the following article from Elle.com Kim Kardashian explains the difference between turnt and lit (up), where the latter appears to convey a stronger meaning:
Turnt (ternt): Not to be confused with "lit," "turnt" is used to describe the atmosphere of a party, event or group of individuals. A party is turnt when the vibes are lifted and participants are all having an amazing time.
Lit (liht): The state of being so intoxicated, turned up or generally in an amazing mood; can be used to describe the state of mind of a person OR the state of a party or event.
It appears that the usage of the term turnt is more common with the digital natives rather than their parents.
As for: ”Do I have to be American to use this slang or is it also used in the UK,” apart from Macmillan Dictionary, both the ODO and Collins Dictionary define turnt as an AmE slang term, anyway given that the term is used in hip hop music and by international Artists such as Miley Cyrus it is reasonable to assume that it is understood and possibly used also in the UK by those who are most exposed to that music.
Solution 2:
The following discussion is from my AmE experience and Green's Dictionary of Slang
The only distinctions I sense between turnt and lit:
lit, adj.: wide-spectrum term of approval, used of events, objects, individuals. ( a second sense - more recent) and seems to be unconfined to describing inebriation/ celebration.
2016 Dly Pennsylvanian 23 Mar. [Internet] Here is a message I texted to my friend, while planning an outing to eat at Zesto’s Pizzeria: ‘Bruh this pizza is lit lets bounce fam’ Here is that sentence translated: ‘[Male friend] this pizza is [good] let’s [leave] [friend]’.
2016 [UK] Guardian G2 8 Aug. [Internet] All modern slang was banned: Like saying: ‘Oh, that’s lit,’ or: ‘Oh, you swagging’.
Whereas turnt and turnt up refer to partying and alcohol. Lit-up is more nuanced: adj. drunk. 2. suffering from a sexually transmitted disease. 3. showily dressed up. 4. extremely intoxicated by a drug. 5. shot. 6. excited. 7. angry.
In AmE lit and lit up are more common in the senses above and used in both the +40 age and the -40 age. Turnt and trunt on are peculiar to the < 30 crowd ... more like gen Z.
All 4 words seem to be crossing the pond from west to east.