ギリギリ
Girigiri
ぎりぎり
A mimetic word (gitaigo) expressing being right at the limit with zero room to spare. Especially common in 'giri-giri safe' (just barely made it) scenarios. Often shortened to 'giri' in casual speech ('giri ma ni atta' — barely made it in time). More of a colloquial expression than slang, but its frequency in daily conversation is extremely high.
Examples
電車にギリギリで乗れた。あと1秒遅かったらアウトだった
I made it onto the train by a hair. One more second and I would've missed it.
Texting a friend on LINE during the morning commute
締め切りギリギリに提出するのやめたい
I need to stop submitting things right at the deadline.
Talking with a friend about university papers
試験ギリギリで受かった。マジで危なかった
I passed the exam by the skin of my teeth. That was seriously close.
財布の中身ギリギリで足りた
I had just barely enough cash in my wallet.