1. A genre of music which originated in the 50's from jazz, blues, and country. It reached it's peak in the late 60's/early 70's and has branched into many different styles, including Heavy Metal, Punk Rock, Hard Rock, Progressive Rock, etc.
The main instruments usually in rock bands are the electric guitar, bass guitar, drums and sometimes keyboards.
2. To have sex. this meaning is no longer in use.
1. Today I went to a rock 'n roll concert. It was pretty okay
2. Me and my girlfiend were rock 'n rolling all night long. It was pretty okay.