r. & i., phr. — Green’s Dictionary of Slang

r. & i. phr.

[abbr. radical (i.e. radical adj.) and intense]

(US campus) extremely exciting or enjoyable.

1981		Eble Campus Sl. Mar. 6: R&I – [...] exciting, extremely enjoyable: ‘Cheryl’s punk-rock party was completely R&I’.
1996		Eble Sl. and Sociability 37: Two kinds of shortening reduce words to letters. The dominant type in college slang is initialism, which names the individual letters: [...] R&I (radical and intense) ‘extremely exciting or enjoyable’.