Yabai

'Yabai' 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.