Overreacting to a somewhat overwhelming situation for the person twilighting, but for others, the situation isn’t that bad. The person tends to overthink, overplan, and hyperventilate.
Friend: Uh, hey, are you doing alright?
Twilighter: Hehe, yeah! I’m doing alright! Just need 7,432 things to do before the big event happens- OH WHO AM I KIDDING I AM NOT OKAY THERE IS SO MUCH TO DO BY TOMORROW!
Friend: Wow, you are twilighting hard.
It's a song, you sex-obsessed idiots! A perfectly innocent Owl City song about a guy who misses his girlfriend (or perhaps even a platonic friend, it isn't clear). Stop trying to turn it into something dirty.
When he uses the term, "Vanilla Twilight", he is literally talking about the color of the sky:
I'll find repose in new ways
Though I haven't slept in two days
'Cause coldnostalgia chills me to the bone
But drenched in vanilla twilight
I'll sit on the front porch all night
Waist deep in thought because when
I think of you I don't feel so alone
Twilightlicious is a brony meme originating from a vocal tweet by Tara Strong, the voice actor for Twilight Sparkle (A character in the rather popular My Little Pony: Friendship is Magic universe)
The format is a small rhyme, usually centered around the basic elements of the character (Twilight being the exception, as the fandom typically portrays her as more of a troll)
"I'm the T to the W-I, L-I-G-H-T, and ain't no other ponytroll it down like me: I'm Twilightlicious"
Twilight Sparkle
Twilight Fangirls (TFs) are typically young, fanatical female fans of the Twilight series of books/films & may be identified by their Hot Topic Twilight tees. TFs travel in small organized groups, or at Twilight-sanctioned events, in larger unorganized packs. Ear protection is a must for bystanders when more than 10 TFs have gathered. TFs should be approached with caution by non-Twilight fans, and safety guidelines should be followed. NEVER state aloud that you are not a Twilight fan, have never read the book(s), or find 'Breaking Dawn' unrealistic in any way. If threatened, back away slowly & repeat calmly "I read the Isle Esmee chapter 27 times!". TFs' greatest wish is to stalk the set of any Twilight film, or - SQUEE!!! - to meet Robert Pattinson.
Twilight Fangirl #1 "OMG, did you hear Rpattz is on the set in Vancouver?"
Twilight Fangirl #2 "I KNOW! Let's go camp outside his hotel (or the hotel we THINK he's at) for 3 weeks!"
TF #1 & TF #2 "SQUEEEE!!!"