Green’s Dictionary of Slang

1. (US campus) excellent, admirable.

1988		Eble Campus Sl. Mar. 10: That’s a trippin’ motorcycle.
1990		Eble Campus Sl. Nov.

2. crazy.

1993		Eble Campus Sl. Apr. 6: tripping – [...] illogical, crazy.
2012		J. Díaz This Is How You Lose Her 116: Two thousand dollars. In 198-. This bitch was tripping.