1. What does it mean?
현타 describes suddenly seeing your situation more soberly and feeling empty, foolish, or disappointed. You will often hear 현타가 오다 or 현타 왔다 after wasted time, a failed plan, or an unflattering comparison.
Also written or said as hyeonta
2. The nuance
The everyday expansion 현실 자각 타임 explains the reality-check sense. The word also has an adult association through 현자타임; the ordinary expression does not necessarily carry that sexual meaning.
3. Examples
“새벽까지 영상을 보다 시계를 보고 현타 왔어.”
I watched videos until dawn, then the time on the clock gave me a reality check.
“여행 끝나고 쌓인 빨래를 보니 현타가 오네.”
Seeing all the laundry after my trip is bringing me back to reality.
Sources
National Institute of Korean Language
References support the meaning and usage. Example sentences are written for NoCapWiki.