Guns N' Roses guitarist Slash paid a surprise visit to Brooklyn's School of Rock yesterday - and when we say 'surprise', we really mean 'surprise'.

A bunch of talented kids were belting out 'Sweet Child O'Mine' - and killing it, by the way - when Slash, taking some brief time away from GNR's reunion tour, joined them on stage for the song, as well as 'Paradise City'.

Needless to say, the band members were all flabbergasted when they saw him, even if it took singer Bobbi McKenzie's a while to cop who was with them.

Watch it below:

Via Uproxx