If you roll 4, keep the standard tuning for that string. 1 or 2 semitones up from standard. Repeat for each string. I believe Soft Machine bass player Hugh Hopper recorded an entire album like this. Depending on the content, this type of recording could well end up just sounding like a mess, but there could well be some interesting conjunctions which might be worth sampling and looping.
Draw say three cards, then obey the instructions.
There's an atmosphere already. Impersonating Random Bands I use a pack of cards given away by the music paper NME, featuring photos of bands. When it comes to say writing a riff, I'll draw two cards and try and play a riff written in the first band's style but played in the second band's style. You could use your record collection - pull out two albums at random. Random Samples I load my sampler with random discs, say three sounds, then create a piece using only those sounds.