If you really want to piss everyone off as you commute to work, this messenger bag with a built in playable electric guitar looks like the tool of choice.
All you have to do is strum away while picking out chords on the fret board, and you can get your Nigel Tufnel on whenever the mood strikes. Your noodlings will be heard through the mini amp attached in the corner, which naturally cranks up to 11.
If you want to get in on a little group action, perhaps you can team up with someone wearing one of those conga drum t shirts.
The Electronic Rock Guitar Bag will be available late next month for about $50.