Yabai

Yabai (ヤバイ) is a Japanese word that means, variously, bad, dangerous, risky, or awesome. It equates approximately to the English words sick and nasty in this regard—the slang usage denotes some degree of admiration.

In yoyo usage, yabai is generally used to describe (and shouted in response to) a particularly risky or difficult trick performed successfully: for instance, a behind-the-back suicide, a blind whip, or an off-axis freegen. This is in contrast to nasty, which has come to refer more to technical, unorthodox, and innovative tricks, and less to simple but flashy and risky tricks.